Rambam - 3 Chapters a Day

See Hilchot Zechiyah UMatanah 1:6.

See Halachah 4.

The manner in which the property must be divided is discussed in Chapter 2, Halachot 14-18.

For each person will not receive a share large enough to be of benefit to him.

The Meiri in his commentary on Bava Batra 11a gives examples of such a situation: two brothers inherit a property, but their testator clearly specifies which portion of the field each one is to receive; two partners buy a property that was divided between two separate owners.

According to the Rambam, the principle to be explained applies with regard to all the types of partnership mentioned in the previous halachah. The Ra’avad differs and maintains that it does not apply when two people bought a property in partnership, because the party who did not desire to divide the property could say to the other: “We did not enter into the partnership with such an understanding.”
The Maggid Mishneh supports the Rambam’s ruling, explaining that the other partner could explain that at the beginning he thought that the partnership would be harmonious, and now he finds it difficult to deal with his partner.

From the Rambam’s words here, it appears that the person can arbitrarily fix the price. From the Rambam’s Commentary on the Mishnah (Bava Batra 1:6), it appears that the person must be prepared to buy and sell at the property’s market value. Note the gloss of the Maggid Mishneh, which touches on this issue. The Tur and the Ramah (Choshen Mishpat 171:6) follow the Rambam’s wording here. Note, however, Halachah 5, which speaks of assessing the value.
The above applies to a price that is more than the property’s market value. A partner cannot employ this principle and offer a price lower than that of the market value. If that were possible, a rich man would take advantage of a poorer man on every occasion [Beit Yosef; Ramah (op. cit.)].

Rashi, Bava Batra 13a, offers a different interpretation, stating: “Either quote a price at which you desire to purchase my share, or I will quote a price at which I desire to purchase your share.” The Shulchan Aruch (op. cit.) quotes the Rambam’s words.

This principle is referred to by Bava Batra 13b with the term gud o agud - “Acquire or I will acquire.”

Our translation follows the commentary of the Maggid Mishneh, who explains that the definition of “made for the purpose of hire” or “made for his personal use” is functional: what the structure is most suited for. This interpretation is also borne out by the Rambam’s ruling at the conclusion of the halachah.
The Kessef Mishneh offers a different interpretation, explaining that the fundamental question is: What was the father’s intent when dividing the property among his heirs?

The rich brother cannot say: “Let each of us rent out our own portions separately,” for such properties are usually rented out as a total unit (Ramah, op. cit.).
The Maggid Mishneh and other commentaries state that if the either brother desires, he can employ the ultimatum of gud o agud and compel the other brother to sell him his share.

Thus, although the poor brother does not receive any benefit from the property, the rich brother is under no obligation to him.

I.e., the property as a whole. Alternatively, he can sell his portion of the property to another rich person who would be able to use it in partnership with his brother (Sefer Me’irat Einayim 271:14).

The Tur and the Ramah (loc. cit.) differ and maintain that if the person does not want to purchase the property for himself, he cannot employ the principle gud o agud. All authorities agree, however, that an heir may borrow to purchase the entire property.

The exact term the Rambam uses to refer to the invasion of privacy, hezek r’iyyah, is defined in Chapter 2, Halachah 14.

The Ra’avad differs with the concept of dividing the use of the property over time, explaining that even if the period for rotation is protracted, it is still undesirable. Instead, the involved parties should be compelled either to accept the invasion of their privacy or to divide the property physically.
The Maggid Mishneh supports the Rambam’s position, explaining that the invasion of property is a totally untenable proposition: Should two married couples share the same bedroom? Nor is the division of a property that is not large enough to divide feasible, for then the portion of the property that each partner would receive would not be of benefit to him.
With regard to a home, the opinion of the Maggid Mishneh is accepted. With regard to a courtyard, however, the Ramah accepts the Ra’avad’s logic.

This phrase applies both to the field and to the courtyard.

The Rambam maintain that the principle of gud o agud applies even with regard to rented property. As mentioned above the Ra’avad differs and maintains that this principle applies only with regard to property received through an inheritance or a gift, for in these situations the two people had no control over whether they became partners. With regard to property purchased or rented in partnership, each of them willingly entered into the partnership and therefore cannot dissolve it at will.
As explained above, the Maggid Mishneh explains the Rambam’s position as follows: At the outset, the person thought that he would appreciate the partnership. As time passed, it became uncomfortable. Therefore, he has the right to dissolve it. The Shulchan Aruch (Choshen Mishpat 171:9) quotes the Rambam’s view.

For, as evident from the previous halachot, it is preferable to divide a property rather than to compel one of the partners to buy the other’s portion according to the principle of gud o agud.
The Tur and the Ramah question the Rambam’s ruling, asking: How is it possible for renters to construct a divider in a rented property?

Implied is that when there was a three-way partnership, with two partners each owning 40% and the third only 20%, even if the division would afford the partners with the larger share a portion of the property that is significant, should the partner with the smaller portion not receive a significant portion, he may nullify the division (Sefer Me’irat Einayim 171:5).

In his Commentary on the Mishnah (Bava Batra 1:6), the Rambam explains that this area is granted in addition to the area of four cubits that is granted to every homeowner in a courtyard so that he can load and unload packages before his entrance.
Furthermore, as will be explained in the notes on Chapter 2, Halachah 1, this applies only with regard to courtyards in country villages, where courtyards are used to pasture animals. Courtyards in a city are divided even if each person will receive a smaller portion of land.

3750 square cubits [Rambam’s Commentary on the Mishnah (op. cit.)].

I.e., it would not be worth the effort to plow, irrigate and do any other work necessary for a field unless it were at least this size.

Where vegetables are grown, and hence a smaller size is also valuable.

Slightly more than 208 square cubits.

1250 square cubits.

I.e., countries where land is scarce and very valuable.

Similarly, all the other measures require a day of work. Sefer Me’irat Einayim 171:8 explains that such a measure was chosen because a worker would not be willing to accept a job that requires less than a day of work.

I.e., in contrast to the field mentioned previously, which is watered by using irrigation ditches. This type of field parallels the garden mentioned with regard to Eretz Yisrael.

See Hilchot Mechirah 21:5, which defines the minimum size of a hall as ten cubits by ten cubits.

I.e., the principle of gud o agud explained above.

I.e., the person is proposing that the other partner be given the minimum size required for the entity, and he would receive the remainder. For example, if a courtyard was seven cubits by four cubits, the partner making the suggestion would receive three cubits by four cubits, and the other, four cubits by four cubits.

For, as stated in Proverbs 15:27 and quoted at the conclusion of Hilchot Zechiyah UMatanah: “One who hates gifts will live.”
When stating this law, the Shulchan Aruch (Choshen Mishpat 171:10) also states that one party cannot compel the other to pay the difference in value between the two portions. The Shulchan Aruch also mentions a differing opinion, which gives one partner the right to compel the other in this regard.
The Shulchan Aruch also mentions that one party may tell the other: “Let us divide the field, and either I or you will pay for the extra portion. If you do not consent to such a division, I will purchase the entire field.”

In cities, by contrast, different rules apply, and a division should be made even if the courtyard is smaller, as the Rambam states in his Commentary on the Mishnah (Bava Batra 1:6).
The Maggid Mishneh and the Shulchan Aruch (Choshen Mishpat 172:1) explain further the rationale for the difference between the two. In a courtyard in a country village, the homeowners acquired the land by taking possession of ownerless property. Hence, it is divided according to the above principles. In a city, however, the land is already divided when purchased or when inherited, and everyone knows which portion of the land is his.

This space is granted so that a person leading a donkey with a burden could unload that burden outside the entrance, as stated in Halachah 3.

Chapter 1, Halachah 4. As the Rambam states in his Commentary on the Mishnah (loc. cit.), this space is used for cattle, sheep and the like.

See Hilchot Shabbat 16:16, from which it appears that ten cubits is the largest possible size for an entrance.
The Maggid Mishneh explains that if the entrance is small – e.g., only two cubits wide – the owner is given only an area two cubits by four cubits. In his Kessef Mishneh (based on the opinion of Rabbenu Asher), Rav Yosef Karo differs and maintains that a person is always given a space at least four cubits by four cubits in front of his entrance. For in a smaller space, he would not be able to unload a burden. And in his Shulchan Aruch (Choshen Mishpat 172:1), Rav Karo quotes the latter view alone.

There is a debate among the commentaries with regard to the status of this four-cubit-by-four-cubit space when the courtyard is not divided. Some consider it to be equivalent to the private property of the owner of the entrance. Others maintain that though it is granted to him for his use, it still can be used by the other partner in the courtyard (Maggid Mishneh in his gloss on Halachah 3).

This teaches that not only is a person granted an advantage over his partner if he owns two houses in a courtyard, but even if he owns only one house and that house has many entrances, he is granted four cubits for each of the entrances.

It is considered as if the other entrances were closed. The Ra’avad objects to the Rambam’s ruling, maintaining that the owner must actually build a structure that singles out one of the entrances. The later commentaries and the Shulchan Aruch (Choshen Mishpat 172:3) follow the Rambam’s approach.

A Greek structure like a porch, with two or three walls. Sometimes it would have a roof with a skylight, and other times it would have no roof at all. See Hilchot Mezuzah 6:3, Hilchot Shabbat 17:35 and Hilchot Sukkah 4:8-9.

A room at the entrance to a gate.

In his Commentary on the Mishnah (Ma’asrot 3:6), the Rambam defines a porch as “An elevated place within the courtyard where there are steps leading to the second-story lofts.”

For all the inhabitants of these structures enter through the porch, and that is where they will unload their burdens.

For the four cubits are granted to enable a person to unload his burden, and that is not necessary with regard to a chicken coop.

If the open portion is facing the courtyard, it is obvious that he is not granted the extra four cubits, for he can unload his donkey in the uncovered portion. Even if the closed portion faces the courtyard, he is not granted the extra four cubits, for he can lead his donkey through the covered portion and unload it in the uncovered portion.

For we assume that ultimately the owner will open the entrance and begin using it again (Sefer Me’irat Einayim 172:16).

Since it is no longer functional as an entrance, we assume that the owner was willing to forgo his right to four cubits in favor of the other inhabitants of the courtyard (Maggid Mishneh).
The Ramah (Choshen Mishpat 172:7) quotes the opinion of the Rivash (Responsum 248) and emphasizes that although we say that the owner forfeits the four cubits in front of his entrance, he does not forfeit his portion in the courtyard and is given an appropriate share if the courtyard is divided.

When a structure is smaller than this, we do not consider it useful as a home, and it will not be necessary to unload a donkey in front of it.

Our translation follows the gloss of the Maggid Mishneh. The Ra’avad offers an interpretation that explains that all the structures in this courtyard are smaller than this minimum size.

Including the four cubits in front of his entrance if his house is large enough.

Although there are also animals kept in the courtyard, the manure accumulates primarily from the excrement and refuse from the houses that is deposited there. Therefore, it is divided according to the number of houses (Maggid Mishneh).

We have chosen this translation based on the gloss of the Maggid Mishneh. See also Chapter 5, Halachah 15.

For it is, like most government levies, a head tax.

I.e., though neither partner can compel the other to accept the division. If they both desire, the division should be carried out.
This concept is obvious; the Rambam – and his source, Bava Batra 1:6 – include it as an introduction to the following law.

This is a token of respect to the scroll.

I.e., a scroll is written containing not only the five books of the Torah, but all the 24 books of the Tanach.

The Rambam’s ruling here appears to be a reversal of his previous conception of the issue. In his Commentary on the Mishnah (Bava Batra 1:6; see Rav Kapach’s translation), he states that if many book of the Tanach were written in one scroll and the partners desired to divide them, they may. This conception is also reflected in Hilchot Sefer Torah 7:15, which speaks of writing the entire Tanach in a single scroll and states that three empty lines should be left between each book, “so that if one desires to divide, he may do so.” In this halachah, by contrast, the Rambam is forbidding such a division.
The Tur and the Ramah (Choshen Mishpat 173:1) state that although one person would be allowed to make such a division, it is a mark of disrespect for the sacred writings for a scroll owned in partnership to be divided in such a manner.
When the Tanach is written in two scrolls, the Tur and the Shulchan Aruch rule that if both partners do not agree to divide the scrolls, even if one desires, they should be left intact.

See Hilchot Mechirah 5:14, which explains that when a kinyan is made concerning a general promise to perform an act, but it does not involve a specific entity, it is not binding.

In this instance, each one has chosen his portion of the property, and the kinyan has confirmed it.

The Maggid Mishneh mentions an opinion that states that it is not necessary for both partners to manifest ownership over their shares. Instead, as soon as one partner manifests ownership over his share, the other acquires his share. For in any exchange, all that is necessary is that one take possession of what is due him. See also the explanation of Sefer Me’irat Einayim 157:5.

The Maggid Mishneh states that with the word “went,” the Rambam indicates that this law applies even if the person went on his own volition, without the other partner watching him or telling him: “Go and acquire it.” The rationale is that this division of property is not a sale, and therefore the laws of transfer stated in Hilchot Mechirah 1:8 do not apply.

Even Ha’Ezel explains that the Rambam is not stating that by manifesting one’s ownership over the property, the division is completed. Instead, the intent is, as stated in Chapter 1, Halachah 1, when two partners each recognize their portion of the property, it is considered as if it has been divided. And by manifesting ownership over a portion of the property, the partners thus designate it as their own.

It appears that the Rambam considers drawing a lot as a kinyan through which one acquires the property. Rabbenu Asher, the Tur and the Ramah (Choshen Mishpat 173:2) state that drawing lots merely identifies the portion of the property each will receive, and one of the brothers must actually take possession of the property for the division to be binding.

When there are only two brothers, the intent is that once one draws the lot for his portion, the other automatically receives the other portion. When there are more than two brothers involved, the Rambam’s words require clarification. The Maggid Mishneh offers several interpretations:
a) that the portions are numbered. Once the elder brother receives his portion through the lottery, the second eldest brother receives the portion next to it, the third eldest the third portion, etc.
b) that once one of the brothers receives a portion by lot, all the other brothers are bound to divide the remainder of the property by lot.
c) that once one of the brothers receives a portion by lot, all the other brothers acquire the remaining property as a collective. One of them may, however, refuse to divide it by lot.

Sefer Me’irat Einayim 173:7 states that this ruling applies only when they divide the property without reckoning the value of each of the shares. If, however, they reckon the value of the shares, each one has the right to the privileges that grant his share value. His statement is discussed by the other commentaries on the Shulchan Aruch.

The comprehension of this halachah depends on several fundamental principles. As indicated in the following halachah, when a person acquires property from a colleague, he is ordinarily entitled to all of the rights which the previous owner had. Thus, the owners of the neighboring properties do not have the right to cut off his irrigation, block his windows, make his ladders useless or the like.
Why is this allowed in this instance? Because the brothers are considered as having purchased the property from each other, and when a person sells property to another person, he does not retain any rights to the property. (See Hilchot Mechirah 25:3.)
Bava Batra 65a entertains another possible explanation of the concept of inheritance, b’reirah – i.e., when each brother receives his share, it is considered as if from the outset the property had been divided in this manner. Thus, he would be able to retain all the rights to the amenities that existed beforehand. The Talmud, however, rejects that definition and considers the division of the property to be equivalent to a sale.

I.e., if one brother’s share of the property lies behind another brother’s share of the property, the one with the innermost share cannot demand right of passage from his brother. Instead, he must be willing to purchase that right.

I.e., one brother received the second storey of a building, and another brother received the first storey and the courtyard next to it. The brother who received the second storey cannot require the brother who received the first storey to allow him to erect a ladder to reach his loft.

The Maggid Mishneh explains that the Rambam explains this principle later, that one brother may build a structure that block off his brother’s window. That brother cannot complain, claiming that the window is necessary for him for light and it may not be blocked off.
The Kessef Mishneh also interprets the Rambam’s words in this manner. Nevertheless, he quotes opinions that maintain that if one brother complains that the other brother’s window intrudes on his privacy, the Rambam requires the brother with the window to close it.

I.e., one may close off the irrigation ditch leading to the other’s field as the Rambam proceeds to explain.

I.e., the brothers’ father.

Who were not partners (Maggid Mishneh).

Who had already divided their inheritance (ibid).

For there is no partnership involved here, and each of the buyers must respect the rights that existed previously.

I.e., even if only one of the partners desires the wall, and the other does not, the one who desires the wall may compel the other partner to participate in its construction.

I.e., there are two aspects to the building of the wall in which each partner must participate. [See Shulchan Aruch (Choshen Mishpat 157:3).]
a) he must pay an equal share of the costs of the wall; and
b) he must give an equal portion of his land on which the wall is constructed, as stated in the following halachah.

I.e., it is a significant factor over which a person is entitled to protest.

As is explained in the coming chapters, there are times when a neighbor waives his opposition to a practice performed by another neighbor. Once he makes such a waiver, he cannot retract, and it has become established that the other neighbor has the right to continue his practice.
This principle does not apply with regard to an invasion of privacy. Thus, the Rambam explains in Chapter 11, Halachah 4:
Why are these damages (including an invasion of privacy) different from all other forms of damage? Because a person is not able to bear these damages. We can assume that he never waived [his opposition to them). For the damage is constant.
The commentaries do, however, note an apparent contradiction to this concept in Chapter 7, Halachot 1-6. See the notes on those halachot.

The Ramah (Choshen Mishpat 157:1) reinforces the Rambam’s ruling, stating that even if there is a local custom not to build a partition in such a situation, we do not follow the custom, but compel the partner to join in building the partition.

See Halachah 18, which graphically outlines this principle.

The Ramah (Choshen Mishpat 157:4, based on the Hagahot Maimoniot) states that if, however, it is local custom to make a divider from a substance less sturdy than reeds or palm leaves, that custom need not be followed.

In this manner, a person of ordinary height will not be able to see over the wall.

This ruling has attracted the attention of the commentaries, for obviously a fence ten handbreadths (approximately 40 inches) high will do nothing to prevent one neighbor from seeing another. Indeed, for this reason, the Ra’avad states bluntly: “This is a mistake. The wall must be four cubits high.”
The Maggid Mishneh defends the Rambam’s ruling, explaining that the garden referred to is a vegetable garden - a workplace - and in such a place, there is no need to protect a person’s privacy. When is that necessary? In the courtyard of a person’s home, where he relaxes and performs private acts. (At that time, a person’s courtyard was often used as a lavatory.) Why then is a partition necessary in a garden? To make a distinction between one person’s property and another, so that it will be obvious if one trespasses. (See Chapter 3, Halachah 6.)
The Sages of Lunil addressed a question to the Rambam, noting that from Bava Batra 2b, it appears that the need for privacy applies also in a garden. In a responsum attributed to the Rambam, two replies are given:
a) The privacy spoken about with regard to a garden is that another person should not see the person’s crops growing, become jealous and cast an evil eye upon them. For this, a partition of ten handbreadths is sufficient.
b) That in truth there is no concept of a need for privacy in a vegetable garden. The only reason a partition is necessary is to safeguard against trespassing. The passage in Bava Batra does not reflect the halachah.
The commentaries also note that with regard to a courtyard, the Talmud uses the terms kotel or mechitzah, which generally refer to partitions four cubits high. With regard to a garden, by contrast, the Talmud uses the expression gadder, which refers to a partition ten handbreadths high.
With regard to this law, the Shulchan Aruch (Choshen Mishpat 158:3) quotes the Rambam’s opinion, but mentions the dissenting view as well.

In the above-mentioned responsa, this law is used as a proof that there is no concept of the need for privacy in a garden. For if so, why would there not be a similar need for privacy in a field?
With regard to trespassing, by contrast, there is no difficulty. In contrast to a vegetable garden, crops are not grown in a field throughout a large portion of the year. And at that time, there is no difficulty with trespassing.

Here too, the above difference of opinion between the Rambam and the others applies. According to the Rambam, a ten-handbreadth divider is all that is necessary, while according to the other views, the divider should be four cubits.

Since this wall is not considered necessary, the other partner is not obligated to take part in its construction. Instead, the partner who desired it must bear the entire burden himself.

Bava Batra 4a explains that the protrusion should be made on the outside for the following reason. If it were made on the inside, the neighbor could also build such a protrusion on his side of the wall and then claim that it is his. If, however, it has to be made on the inside, he would have to cross into his colleague’s property to build it, and that would present a difficulty.

For the wall was built on his land, with his stones. Bava Batra (Ibid.) states that even if the stones fall into the other partner’s property, he must give them up.

Indicating that the wall was built in partnership. This is preferable to leaving no sign at all. For if no sign is left, it is possible that one of the partners will build a protrusion on the wall to indicate that the wall belongs to him.
Although we consider the possibility of fraud in this instance, we do not consider the possibility that one colleague will destroy the protrusion built by his colleague, because it would be obvious that the facade of the wall had been changed.

Because they both contributed to its construction.

I.e., without telling him that it is connected to other gardens and must be divided (the Rambam’s Commentary on the Mishnah (Bava Batra 1:22)].

The Ra’avad maintains that the seller and the purchaser should build the fence together. The Maggid Mishneh explains that the Rambam’s decision echoes his ruling in Hilchot Mechirah 21:22 which states that when a person purchases a portion of a field from a colleague, it is the purchaser’s responsibility to erect a fence dividing the two portions.
The Shulchan Aruch (Choshen Mishpat 158:2) quotes the Rambam’s opinion, but prefaces it with the words: “There is an opinion, which states....” The Ramah and the Tur rule that the buyer and the seller are considered as two partners who divide a field and that they should follow the local custom.

The Maggid Mishneh questions the Rambam’s source for this ruling, and the Kessef Mishneh offers several possible interpretations. A clear understanding of the Rambam’s position can be derived from his Commentary on the Mishnah (Bava Batra 1:2). There the Rambam states that when a person buys a field from a colleague, the purchaser is obligated to build a fence to divide the two gardens, even if the seller did not specify that it would be necessary to do so when he sold the garden.

With regard to this point as well, the Shulchan Aruch (loc. cit.) quotes the Rambam, while the Ramah and the Tur state that local custom should be followed.

For generally, fences are not erected in fields (Rambam’s Commentary on the Mishnah, loc. cit.).

For the width of the entire wall is six handbreadths.

For when the stones are hewn, their length is reduced.

The bricks are three handbreadths long, as reflected in the following clause. Nevertheless, since they are broken, each of the neighbors must give another half handbreadth for the extra mortar in between.

If, however, the stones are not seen, we accept that colleague’s claim, based on the principle of migo. Had he desired to lie, he could have claimed that he already returned the stones to his colleague (Maggid Mishneh).

By bringing witnesses who support him.

These points are obvious from the Rambam’s rulings in the previous chapter, Halachot 14 and 16.

For four cubits is sufficient to prevent one colleague from looking at the other in his private domain.
The Kessef Mishneh [quoting from another version of the text] states that this applies even if the wall was originally higher than four cubits. A partner can refuse to rebuild the wall to its original height.

The colleague who builds the wall must take full financial responsibility for his initiative. If the other partner does not desire the added height of the wall, he cannot require him to share in its costs. Needless to say, both partners must share in the initial four cubits of the wall, as stated above.
From the Rambam’s words, it would appear that either colleague has the right to take the initiative and build the wall to whatever height he desires. [In his Commentary on the Mishnah, Bava Batra 1:4, the Rambam states this explicitly.] With regard to this issue, the Shulchan Aruch (Choshen Mishpat 157:9) quotes two opinions. The first states that if the other partner protests and claims that by building the wall higher the builder will prevent the other from using the wall, he can hinder him from building it, if that is the local custom. The second maintains that although the other partner cannot prevent the builder from building, the builder must reimburse him for any loss he suffers if he lodges a protest.

I.e., in addition to his share in the original four cubits, he must pay half the costs of the next two cubits. For his actions indicate that he desired that the wall be built at least six cubits high.

Had he not so desired, he would not have built his own wall six cubits high.

By using the addition his colleague made for his own purposes.

This applies even if we know that the plaintiff was the only one who took part in the actual construction of the wall, and even if there are witnesses that the plaintiff asked the defendant to help, and the defendant refused [Shulchan Aruch (Choshen Mishpat 157:8)].
In his Commentary on the Mishnah (Bava Batra 1:4), the Rambam explains the rationale for this ruling: Since it is well-known that he is liable for this obligation, we assume that he paid.

A less severe rabbinic oath, which is required of anyone who denies entirely a claim issued against him.

The Shulchan Aruch (op. cit.) explains what type of proof the plaintiff could bring:
a) that witnesses were with him for the entire time from the moment he began the construction until the present, and they did not see the defendant pay him;
b) that witnesses will testify that the plaintiff sued the defendant to require him to help in the construction of the wall; although the court obligated him to do so, he refused.

In the above source, the Rambam explains the rationale for this decision: Since the defendant was not obligated to pay his share for the wall until he showed that he desired its construction, and the plaintiff had not demanded payment beforehand, we tell the defendant: “How could you have paid him when you do not know that you are obligated to pay?”

The oath is required because there is still the possibility that the defendant paid; there is no chazakah that he did not. The commentaries question why this oath is not mentioned in Hilchot Sh’vuot, Chapter 7, among the Rambam’s listing of those who are required to take an oath holding a sacred object before expropriating their due.
Note the Tur and the Sefer Me’irat Einayim 157:31, who quote opinions of Rishonim who do not require an oath.

I.e., in the midst of repairing the walls of his own ruins, he builds walls that are functional for the other owner.

I.e., even if the other colleague encloses this portion. Certainly, this applies if the owner encloses the fourth side, as stated in the following halachah.

For all that is necessary is a divider of four cubits, as stated above.

The Vilna Gaon asks: Why should we make the owner of the enclosed ruin pay for the enclosure? He did not commission it, nor did he give any indication that he desires it?
He explains that the situation can be compared to that of a person who plants a field belonging to a colleague without his permission. In such a situation, the Rambam rules (Hilchot Gezelah Va’Avedah 10:4) that the person who plants is given the market value for his work. Similarly, in this instance, he should be given the market value for the wall.
This ruling depends on the conception that although the owner has not stated that he wants to enclose his ruin, it is taken for granted that it is to his benefit that he do so. Note, however, Hilchot Gezelah Va’Avedah 10:9, which states that one should not necessarily assume that a person would desire to have his ruin rebuilt.

For only then does the owner of the enclosed ruin become a part-owner of the wall.

This expression indicates a conclusion for which the Rambam has no explicit source in the Talmud or other Rabbinic writings.

The Ra’avad differs with the Rambam concerning this point, maintaining that, on the contrary, the owner of the enclosed ruin is gaining more in such an instance. He should be allowed to use the wall and should give the builder of the wall a legal document acknowledging that the space for the wall belongs entirely to him.
From the gloss of the Maggid Mishneh, it appears that the Rambam’s opinion is that if both partners desire, an arrangement similar to that suggested by the Ra’avad can be worked out, but neither is obligated to consent to it.

The commentaries note that in the original Hebrew, the subject haketalim, employs a plural form, but the verb hayah is in the singular. Even Ha’Ezel suggests that the text should read “the place of the walls.”

The Maggid Mishneh and the Kessef Mishneh maintain that this applies only if the owner of the enclosed ruin encloses the fourth side with a wall similar to that built by the other person. If, however, he builds the fourth wall with a less sturdy structure, he is not required to pay half the costs of the other three sides. Instead, he is merely required to pay half of what it would cost to enclose those three sides in the same manner as he enclosed the fourth. This understanding is reflected in the ruling of the Shulchan Aruch (Choshen Mishpat 158:7).

Although the Rambam - and similarly our translation - employs the term guard rail, it would appear that the intent is merely to borrow the Biblical term (Deuteronomy 22:8). Every roof must have a guard rail to protect people from falling (see Hilchot Rotzeach USh’mirat HaNefesh, Chapter 11), but that guard rail does not have to prevent someone from seeing onto - or from - the roof. This halachah speaks about constructing a divider on the roof, not for the purpose of safety, but for the purpose of privacy.

I.e., the roofs are horizontal and not slanted, so that a person could stand there.

Four cubits high.

I.e., neither is required to erect a partition for the entire length of the roof. Instead, each one should erect a partition for slightly more than half. See the accompanying diagram.
The Construction of Guardrails on Roofs Which Face Each Other
a) one home
b) a second home
c) the public domain
d) a guardrail extending more than half the length of the roof
e) a guardrail extending more than half the length of the roof

And therefore, he may protest to his colleague: “Why must I build a partition so that I don’t see you; the people in the public domain can always see you?”

Since the distance between the roofs is not that far, one can see even at night. The darkness would prevent people in the public thoroughfare, by contrast, from seeing.

We are speaking about properties situated on an incline, and so the courtyard is the same height as the other person’s roof. The properties need not be next to each other. Instead, as reflected in the previous halachah, if they are close to each other and on the same level, there is a question of the invasion of privacy, and a divider is required (Sefer Me’irat Einayim 159:7).
A House Built on a Slope Whose Roof Is on the Same Level as An Adjoining Courtyard
a) the house b) the partition c) the courtyard

The Shulchan Aruch (Choshen Mishpat 160:1) explains that the owner of the roof is considered to be damaging his colleague, the owner of the courtyard, by invading his privacy. Therefore, he is responsible to eliminate that damage by constructing a wall.
The owner of the courtyard, by contrast, is not considered to be invading the privacy of the owner of the roof. The Beit Yosef (Choshen Mishpat 159, 160) explains this point as follows. It is taken for granted that the owner of a courtyard will be constantly using his courtyard, while the owner of a roof - even a flat roof that is fit to be used - will use it only from time to time. Thus, the owner of the roof will always consider that the owner of the courtyard is possibly watching him and will take whatever precautions necessary. The owner of the courtyard cannot take such precautions, because he does not know when the owner of the roof will be there. Hence, the owner of the roof must take precautions so that he does not invade the privacy of the owner of the courtyard. The owner of the courtyard, by contrast, does not have any responsibilities to the owner of the roof.
The commentaries explain that according to the Rambam, the owner of the courtyard is not responsible for paying anything for the construction of the wall. For the responsibility to remove the invasion of privacy is solely that of the owner of the roof. The Maggid Mishneh and the Shulchan Aruch (op. cit.), however, state that the owner of the courtyard should share in the costs of the bottom ten handbreadths of the wall. For he is also responsible for making a distinction between the properties, as reflected in the latter clause of this halachah.

As reflected in the continuation of the Rambam’s words, and as emphasized by the Ra’avad, this refers to slanted roofs, which are not fit for use.

Each one is considered as having invaded the privacy of the other.

I.e., he claims that he need not suffer because his colleague’s courtyard is lower.

The Maggid Mishneh explains this ruling as follows: Since the wall must be built on the land belonging to both neighbors, and the land belonging to one is lower than that of the other, the owner of the upper courtyard must contribute to the cost of building the half of the wall that must begin in the property of the owner of the lower courtyard.
Afterwards, the owner of the lower courtyard must continue to share in the cost of the wall until he cannot see the owner of the upper courtyard from below. If, however, the owner of the lower courtyard has difficulty seeing the owner of the upper courtyard because of the difference in height, it is necessary only to build a small partition.

For, as explained in the notes on the previous halachah, it is not considered as if the owner of the courtyard invades the privacy of the owner of the roof at all. Instead, the owner of the roof must build a wall on his roof that extends four cubits above the ground of the courtyard. (According to the Rambam, it is not necessary for the owner of the courtyard to contribute to the building at all. According to the other opinions mentioned above, he must contribute towards the building of a divider ten handbreadths high.)
[This reflects one opinion in the Shulchan Aruch (Choshen Mishpat 160:1). A second opinion is that if the roof is four cubits or more below the courtyard, it is not necessary to build a divider.]

Perhaps the example of a garden was chosen because according to law, all that is necessary in a garden is a divider that is ten handbreadths high (Chapter 2, Halachah 16). If one of the neighbors desires to build a more substantial structure, he must build it at his own initiative and expense.

For they present an obstruction to his neighbor’s garden.

I.e., you may keep the stones, but you must remove them.

For a person cannot compel another to acquire any property.

The Maggid Mishneh cites a question asked by the commentaries: Since a person acquires an article placed in his domain by virtue of its presence there, why is it necessary for the person to remove them in order to acquire them? Seemingly, his consent alone should be sufficient.
The commentaries explain that a person’s courtyard can acquire an article placed there when the person placing it there desires to transfer ownership of it. In this instance, we do not suspect that the owner of the wall genuinely desired to transfer ownership of his stones. Instead, we assume that he was merely procrastinating.
In that vein, the Rashba states that it is only when the owner of the garden removes the stones in the presence of their owner that he acquires them. When he sees him taking his stones and does not protest, we assume that he genuinely desires to relinquish ownership. Otherwise, we have no proof of that. Nevertheless, Sefer Me’irat Einayim 166:2 does not accept that argument and maintains that even when the owner of the garden moved them without the owner of the wall watching, the owner of the wall is considered to have consented.

The one closest to the spring.
The rationale is obvious. If the first owner cannot take water from the spring, none of the others will be able to take water either.

The owners of the higher gardens are not concerned with the water once it passes through their property. They do not derive any advantage if the owners of the lower properties have water. Therefore, they are not required to participate in their costs.

For rain water or for sewage.

Here too, the rationale is obvious, if the drain is not useful for the lowest property, none of the higher properties will be able to use it either.

For the inhabitants of the lower properties do not derive any benefit from the drain in the higher properties. Indeed, if anything the fact that the water from the higher property drains through their property is a nuisance.

The commentaries explain that this, like the ruling in the final clause of the halachah, was instituted as an expression of “the ways of peace.”

This ruling, a translation of the Talmudic expression kol d’alim g’var, is rendered because there are two opinions regarding this law in the Talmud (Gittin 60b), and the Talmud does not reach a binding conclusion. Therefore, the situation is left to every set of neighbors to settle on their own.
There is a difference of opinion with regard to the meaning of the phrase kol d’alim g’var. Some interpret it as meaning: “Whosoever’s claim appears stronger.” Others - and this appears to be the interpretation in this instance - state that it means simply: “Whoever is stronger than his colleague and can enforce his position.”

The Tur and the Ramah (Choshen Mishpat 170:2) state that this refer to a cistern that existed before the irrigation ditch, and the irrigation ditch flows directly over it. Otherwise, since the owner of the cistern is obstructing the natural flow of the irrigation ditch, the principle of “who overcome, prevails,” would seem to apply.
Sefer Me’irat Einayim 170:3 emphasizes that the Rambam does not share that conception, and seemingly neither does the Shulchan Aruch, which quotes the Rambam’s ruling verbatim.