Kri'at Shema - Chapter Three

In the second chapter, the Rambam discussed various halachot regarding the proper state of mind necessary for the reciting of the Shema. In Chapter 3, the discussion centers on the proper physical surroundings required for the performance of the mitzvah and those situations that preclude its fulfillment.
Deuteronomy 23:10-15 discusses the laws regarding army camps, stating the fundamental guiding principle: “God walks among your camp, therefore... your camp must be holy” (ibid.:15). Included in that guideline is the obligation for every soldier to carry a spade in order to cover his excrement (ibid. 23:14). (See positive commandments 192 and 193 in Sefer HaMitzvot; Hilchot Melachim 6:14-15.)
Since these laws were instituted because “God walks among your camp,” it follows that they are also relevant when the Jews attempt to relate to God through prayer. Thus, these verses also serve as the source for the laws regarding the prohibition of reciting the Shema in the presence of feces as discussed in this chapter.
Commenting on the above verses, the Sifri states: “From here, we are taught that one should not recite the Shema next to the soakings of the clothes’ washers”—i.e., that one should not recite the Shema in a place where there is a foul odor or an unclean substance.

Rabbi Yochanan says: “A person who wants to accept upon himself the kingship of Heaven in the most complete fashion should see to his bodily needs, wash his hands, put on tefillin, recite the Shema and pray.” Rav Chiyya bar Abba equates this process with the building of the altar and the bringing of sacrifices, based on the verse in Psalms 26:6: “I wash my hands in cleanliness and circle Your altar, O God” (Berachot 14a-15a).

This is the case even if one’s hands are not obviously dirty, because hands tend to touch the covered parts of one’s body, and thus, require the washing of hands.
The Rambam holds that a blessing is recited after one washes one’s hands before Kri’at Shema. (See Hilchot Berachot 6:2.) The requirement to wash our hands upon rising in the morning was established by the Sages as a preparation for Kri’at Shema and the Amidah. A blessing was instituted for this act and, therefore, a blessing is recited every time that one washes his hands before Kri’at Shema or the Amidah. (Rabbenu Asher also shares this position. See his notes to the ninth chapter of Berachot.)
The Rashba explains, however, that the blessing על נטילת ידים was instituted as one of the many blessings that one recites upon rising in the morning (השחר ברכות). In response to receiving anew his soul from Heaven, one is obligated to praise and thank God. In that context, the Sages also instituted the requirement that he sanctify himself for his day’s worship, just as the priests in the Temple did—i.e., by washing his hands with water from a vessel. There is, however, no intrinsic connection between the washing of hands, and Kri’at Shema and the Amidah. Therefore, the blessing is recited only in the morning upon rising.
The Shulchan Aruch, Orach Chayim 92:5 and 233:2 agrees with the Rashba and does not require a blessing upon washing hands in preparation for Kri’at Shema and the Amidah. (See also Beit Yosef on Tur, Orach Chayim 7, Magen Avraham, the Mishnah Berurah on Orach Chayim 4:1, and the Shulchan Aruch HaRav, Orach Chayim 4:1.)

See Chapter 1, Halachah 11. According to the Rambam’s position, this refers to ten minutes before sunrise. The differing opinions will interpret it to mean that the third hour of the morning will soon pass.

In contrast, in Hilchot Tefillah 4:2 and 4:3, the Rambam obligates one to travel a substantial distance (up to 4 kilometers) to find water in order to wash his hands before the Amidah. Rabbenu Manoach explains that, in the latter instance, the law is stricter because there is a longer time during which one may recite the Amidah—until the end of the fourth hour. Hence, we need not worry that he will miss the proper time.
The Kessef Mishneh adds that we are stricter regarding the time of Kri’at Shema since it is a Scriptural obligation. Were a person obligated to travel great distances in search of water, he might miss the proper time of Kri’at Shema simply in order to fulfill the Rabbinic ordinance regarding washing his hands.

Berachot 15a explains that Psalms 26:6, the verse from which the obligation to wash is derived, does not state “I wash my hands in water,” but rather binikayon, “in cleanliness.” Thus, anything useful for cleaning the hands may be used, although water is most preferable.

Berachot 15a uses the expression “anything that cleans.” Therefore, rough clothing is also useful for this purpose (Kessef Mishneh), as is cleaning one’s hands by rubbing them against the wall (Shulchan Aruch, Orach Chayim 92:6).

When describing the proper environment for an army camp, Deuteronomy 23:15 states: “He shall not see any nakedness among you.” Implied is that nakedness, and also a place where people undress even if no naked people are there, is not appropriate for “God to walk among you.” Hence, neither Shema nor the Amidah can be recited there. See Halachot 16-19.

Berachot 26a and Shabbat 10a explain that even without the presence of fecal matter, a latrine is not a fit place for prayer.

Berachot 18a. Proverbs 17:5 states: “The one who mocks the poor (rash) reproaches his Creator.” The Talmud also explains that this term also refers to the dead and derives many halachot regarding conduct in the presence of a corpse from this verse. It is forbidden to wear tefillin or carry a Torah scroll in a graveyard, since one would, in a certain sense, be mocking the dead, who are unable to perform mitzvot. This is the case regarding Kri’at Shema also.

Sotah 43b teaches us that a corpse “occupies” a space of four cubits regarding Kri’at Shema.

The Kessef Mishneh explains that the Rambam’s position is based on the notion of קנסוהו רבנן, i.e., that the Rabbis disallowed the recitation of the Shema even in a case where one was unaware of the impropriety of the place, so that people would exercise greater care in this matter.
The Ra’avad differs with one aspect of the Rambam’s decision. He maintains that although it is certainly forbidden to read the Shema in the presence of a corpse or in a graveyard, the violation of this prohibition does not override the fact that one did recite the Shema. Therefore, he need not repeat it. The Shulchan Aruch, Orach Chayim 71:7, follows the Rambam’s ruling.

The designation alone of a building for such a purpose attaches a stigma to it such that it is unfit for the Shema to be recited inside it.
Shabbat 10a raises the question of praying in such a building and does not resolve the issue. The Ra’avad therefore disagrees with the Rambam and feels that such a doubt should be dealt with leniently—i.e., that we should allow one to pray inside such a building.

Rav Adda bar Ahava states: “One may pray in a bathhouse” (Shabbat, loc. cit.) The Talmud explains that he was referring to a new bathhouse. Rashi explains that this means that it has been designated as such but no one has ever bathed there. The Sages felt the stigma attached to a bathhouse was not as severe as that attached to a latrine and hence, were more lenient.

Nedarim 7a mentions this case within the context of the Talmudic concept of yad (“a handle”) of a vow or other significant utterance. This term refers to expressions that are not completely self-explanatory and leave room for doubt. Just as the handle of a cup is not the essential part of the cup, and yet when one grabs the handle the whole cup follows, so, too, a statement can be made which in itself is incomplete or unclear, but seems to contain within it an intimation of a complete idea. In our case, it is unclear whether the word וזה refers also to a latrine or to another idea altogether.

Nedarim 7a deals explicitly with this case and interprets “Also this” as clearly referring to a latrine.

In contrast to the previous cases in this halachah, this applies to the courtyard of a bathhouse which is being used.

Shabbat 10a distinguishes between the middle room where some people are clothed and others naked, and the courtyard of the bathhouse, where everyone is clothed. Only there, in the courtyard, is one permitted to recite the Shema. In the middle room one is prohibited from reciting Kriat Shema even if there are no naked people there at the time (Shulchan Aruch HaRav, Orach Chayim 84:1).

E.g., Torah study or prayers.

Berachot 24b quotes various verses which equate such utterances with very serious transgressions.

Psalms 12:7 states: “The words of God are pure words.” Therefore, it is improper for them to be uttered or contemplated in a place of filth (Sefer Chassidim 546).

Zevachim 102b relates that Rabbi Elazar ben Rabbi Shimon thought of a halachah while at the latrine. The Talmud then asks how he could have done such a thing, since such thought is forbidden. They explain that a state that is unavoidable (ones) is different.
Rashi explains that Rabbi Elazar was so immersed in his Torah study that he thought about it even against his will. Rabbenu Manoach quotes the Ra’avad as saying that in such a case, thoughts of Torah are permitted when at the latrine. Sefer Chassidim (loc. cit.) advises that people should force themselves to think of mundane matters in order to avoid thoughts of Torah in unclean places. (See Magen Avraham, Orach Chayim 85).

The Rama (Orach Chayim 3:2) mentions that it is preferable not to speak at all at the latrine.

The terms used to praise God, but which are not His specific names and may therefore be erased (Hilchot Yesodei HaTorah 6:5).

רחום in Hebrew. The Ra’avad disagrees with the Rambam and states that since this attribute is used as a name only in relation to God, it may not be uttered in the latrine. Rabbenu Yonah quotes Psalms 112:4 as a source that uses the term רחום in relation to a righteous person, thereby refuting the Ra’avad. The Shulchan Aruch, Orach Chayim 85:2 accepts the Rambam’s position.

Even if the intent is to refer to G‑d, since these names are not fundamentally holy, they may be used in such a place (Mishnah Berurah 85:11).

In Hilchot Yesodei HaTorah (loc. cit.) the Rambam gives a larger list than appears here and includes descriptive terms used to refer to God, e.g., the Great One, the Mighty One, and other names.
The Kessef Mishneh expresses surprise at the exclusion of the term שלום. Shabbat 10b explicitly mentions it as forbidden to be uttered in the bathhouse—all the more so at the latrine—since it is specifically used as a name of God (Judges 6:24). The Magen Avraham (Orach Chayim 84) also forbids the utterance of שלום in such places.

This refers only to the bathhouse for these statements may not be recited in a latrine even though it has not been used.

Shabbat 40b quotes an instance in which Rabbi Meir explicitly mentioned a halachah in the bathhouse in order to stop a pupil from transgressing. Accordingly, it distinguishes between distancing someone from wrongdoing, which is permitted, and uttering other words of Torah, which is forbidden (as mentioned).

Even if it emits no foul odor. (See Rashi on Berachot 25a).

Skins were frequently soaked in feces in the process of making them into leather.

This includes chicken or donkey dung (Kessef Mishneh based on the Jerusalem Talmud, Berachot 3:5).

I.e., the Shema may be recited next to it. The Ra’avad disagrees with the Rambam and quotes the Jerusalem Talmud, which includes donkey urine as one of those items that prohibit Kri’at Shema. The Kessef Mishneh explains that the teaching on which the Rambam based his decision most probably mentioned donkey dung (as mentioned in the previous comment) and not donkey urine. The Shulchan Aruch, Orach Chayim 79:6 reflects the position of the Ra’avad.
Rabbenu Asher points out that the Rambam mentions animal urine alone as not being problematic, thereby indicating that animal dung (e.g., cow or horse excrement) would be problematic. Rabbenu Asher himself sees no room to prohibit animal dung, since it is never mentioned in the Talmud as problematic. In his Kessef Mishneh, Rav Yosef Caro explains that the Rambam’s position is that animal dung is prohibited only if its smell causes discomfort, and that the extent of this discomfort is somewhat subjective. Therefore, the Rambam did not mention it explicitly. And in his Shulchan Aruch, Orach Chayim 79:4, Rav Yosef Caro rules in accordance with this understanding of the Rambam.

The weight of an olive cannot be determined by weighing an average olive today. Rather, it is dependent on the measure established by the Sages, and this is the subject of debate by the Rabbinic authorities. The Pri Chadash (Orach Chayim 486) explains that the Rambam considers an olive as one third the size of an egg (כביצה, a more familiar Talmudic measure). In terms of modern measurements, this olive size would be between 19.2 and 24 grams, according to various Halachic opinions.
Tosafot (Chullin 103a) differs, and defines the size of an olive as one half the size of an egg (between 28.6 and 36 grams according to the various opinions).

There are five types of grain cereal—wheat, barley, oats, spelt and rye (See Hilchot Chametz U’Matzah 5:1).

This measure (אכילת פרס in Hebrew) is significant in halachah. Just as the Torah requires a specific quantity, the size of an olive, as regards many of the mitzvot and prohibitions concerning eating, it also specifies a limited period in which this amount of food must be consumed: כדי אכילת פרס the time it takes to eat this measure.
This measure is also a point of Rabbinic controversy. Here and in Hilchot Ma’achalot Asurot 14:8, the Rambam defines אכילת פרס as three eggs. Rashi (Pesachim 44a) takes a more lenient view, defining it as four eggs.
This halachah is based on the principle that it is unnecessary to distance oneself from a child’s feces or urine which does not have a foul odor. Thus while a child’s sole source of nourishment is nursing, there is no prohibition. However, grains emit a foul odor after being digested (Rashi on Succah 42b). Therefore, once the child begins eating them, the Shema may not be recited in the soiled child’s presence

Berachot 25a defines this as feces which when either: a) rolled, or b) thrown will not crumble. At such a time, they are regarded like a shard. The Rambam chooses the stricter of these two opinions—i.e., that if thrown, it still retains its shape and is, therefore, forbidden (Kessef Mishneh).

Rabbenu Manoach states that it must really crumble and not just break into two pieces.

However, if they still emit a foul odor, the Shema may not be recited next to them, as mentioned in Halachah 12 in regard to a foul smell emanating from a substance (Kessef Mishneh).

Berachot 25a-b records the disagreement between Rabbi Yosse and the Sages regarding the degree of moisture necessary to be problematic. The Sages require that the hand be moist enough so that it itself would dampen something it came into contact with, while Rabbi Yosse requires moisture only on the hand itself. The Rambam decides the halachah in accordance with the position of Rabbi Yosse.

Even if a mark is still visible on the ground (Berachot 25a).

This halachah is based on the Mishnah (Berachot 22b). In modern measure, a cubit is 48 centimeters according to Shiurei Torah.

Berachot 26a modifies the Mishnah quoted (ibid. 22b): Ravvah says: “We learned (in our Mishnah) only regarding ‘behind him,’ but ‘in front of him’—he should distance himself until he cannot see it.”
The Rambam equates “its being at the side” with “behind him.” The Kessef Mishneh suggests that this only applies when it is impossible to move in front of the feces. However, if he is able to walk in front of them, he must. Nevertheless, the Shulchan Aruch, Orach Chayim 79:1 states simply that “to its being at the side” is equated with “behind him.”
The Magen Avraham quotes the statement of the Kessef Mishneh and mentions that if the feces were at the person’s side and slightly in front of him, they would be considered as if they were in front. Therefore, one would be required to move until they were out of sight.

Even at night, he must distance himself to the same the degree that he would in the daytime (Shulchan Aruch, Orach Chayim 79:1). This is also the case with a blind person.

I.e., that one must distance oneself four cubits from urine and feces.

I.e., approximately 80 centimeters according to Shiurei Torah.

He is considered to be in a different place (Berachot 25b).

Rabbenu Asher suggests that this leniency applies even if he can see the excrement. The Rashba, however, disagrees and states that if he can see it, he is forbidden to recite the Shema. The Shulchan Aruch, Orach Chayim 79:2 quotes both positions. The Magen Avraham suggests that closing one’s eyes would be enough to allow one to recite the Shema.

This is not mentioned in the beraita in Berachot 25a. However, immediately after the halachah regarding separations, the beraita then states that a foul smell emanating from a solid substance prohibits recitation of the Shema. Hence, the Rambam associates the two halachot.
The Kessef Mishneh mentions that, based on the Rambam’s position, one should be careful not to recite the Shema or pray in a house with a foul odor, even if the odor is emanating from a different house. The Shulchan Aruch, Orach Chayim 79:2 quotes this, but also mentions the positions of Rabbenu Yonah and Rabbenu Asher, that a separation is sufficient even if an odor remains.
The Magen Avraham suggests that it is best to be strict in such a case. However, he grants one leniency. Generally, one must distance oneself from an odor even if he himself cannot smell it. However, in this instance, a lack of smell would be enough to permit the reading of the Shema.

See Berachot 25b.

Berachot 25b equates this with a case where the feces are covered.

A revi’it whose modern equivalent is 86.4 cc according to Shiurei Torah.

I.e., regardless of the size of the discharge of urine, one revi’it is sufficient (Kessef Mishneh).
Rabbenu Asher explains that the Rambam mentions explicitly one discharge of urine in order to tell us that a revi’it must be added for each discharge of urine—i.e., two revi’iot for two, three revi’iot for three, etc.
The Kessef Mishneh explains that there is no difference if the water is there before the discharge of urine or is added afterwards.

See Berachot 25b.

This is considered as a sufficient covering. We do not consider his sandal to be part of his body, in which case, the feces would not be considered covered. The Shulchan Aruch, Orach Chayim 76:2 adds that there must be no foul smell from the צואה.

After stating the halachah that one may put one’s shoe on top of the hole in the ground, Berachot 25b questions the law when excreta is stuck to a person’s shoe, and leaves the question unresolved (תיקו). Accordingly, the more stringent opinion is followed.
The Rambam explains that this applies if there is any contact between the shoe and the feces. However, the Ra’avad maintains that this only applies when the feces are actually stuck to the shoe. The Shulchan Aruch, Orach Chayim (loc. cit.) 76:2 supports the Rambam’s position.

See Berachot 25b.

Berachot 25a states simply “if there are feces on one’s skin.” The Rambam explains this as referring to a residue of feces—i.e., a stain, with no actual substance.
Rabbenu Asher explains that this applies when there is actual substance on the person’s skin, but it is covered by his clothing. The Shulchan Aruch, Orach Chayim 76:4 reflects the understanding of Rabbenu Asher. However, the Magen Avraham favors the Rambam’s position.

This decision is disputed in Berachot, loc. cit. Though most Halachic authorities accept the decision quoted by the Rambam, Rabbenu Chananel differs. The Shulchan Aruch HaRav 76:4 advises that one follow the opinion of Rabbenu Chananel.

I.e., his anal opening.

See Yoma 30a.

The position of Rabbenu Chananel mentioned above.

Even though in strict halachic terms, one need not heed their teaching, it is fitting to do so, since it is improper to recite the Shema with dirty hands (Kessef Mishneh).

E.g., feces are found on the ground and a foul odor is emanating from them (Rashi, Berachot 25a).

Berachot 25a records a disagreement between Rav Huna and Rav Chisda. Rav Huna states that one must distance himself four cubits from such a substance. Rav Chisda requires that one must distance himself four cubits from the point where there is no foul smell.
The Rambam holds that the halachah follows Rav Huna. In the previous halachah, the Rambam also supported Rav Huna’s position, since Rav Chisda was a student of Rav Huna and thus, of lesser stature. In contrast, the Ra’avad accepts Rav Chisda’s position. The Shulchan Aruch, Orach Chayim 79:1 quotes the Ra’avad’s view.

Rabbenu Manoach points out that this halachah applies only in the case where the substance is to his side or behind him. However, if the substance is in front of him, we have already learned in Halachah 8 that he must distance himself until he can no longer see it.

Rashi differs and explains that Rav Huna allows the Shema to be recited four cubits from the substance even if the odor has not subsided.

I.e., he does not necessarily have to distance himself four cubits. The Ra’avad also disagrees concerning this point and requires that one distance himself four cubits from the point at which the odor ceases. The Shulchan Aruch (loc. cit.:9) accepts the Rambam’s position.

In Hebrew גרף ועביט, both of which are clay vessels. גרף is used for excreta and עביט for urine (Rashi on Berachot 25b).

Among the present applications of this halachah is the need to distance oneself from a child’s potty when reciting the Shema and other prayers even if it does not contain feces or urine.

Berachot 25a mentions a difference of opinion between Ravvah and Abbaye about this case. Here, as is the general rule, the halachah follows with Ravvah’s opinion.

A pig is always rummaging around in garbage and excrement and, therefore, is judged as moving excreta at all times.

Some Rishonim distinguish between moving feces and a stationary substance since in the former case, the feces will continue to proceed further. This would appear to be the Rambam’s opinion, as obvious from the contrast between a stationary substance emitting a foul odor where we are required to distance ourselves until it is out of sight (Halachah 8) and this halachah.
The Kessef Mishneh explains that there is no Talmudic source for this distinction. Therefore, he explains that there is no difference between stationary and moving feces and that this halachah only applies to feces which are behind a person. If the feces are in front of him, the Shema cannot be recited until they move out of sight.
In the Shulchan Aruch, Orach Chayim 76:3, Rav Yosef Caro follows his explanation in the Kessef Mishneh. However, the Bach and the Magen Avraham (76:2) make the distinction between moving and stationary feces.

I.e., a place where there is a foul odor emanating from excreta or urine.

Berachot 24b relates:
Rav Huna said in the name of Rabbi Yochanan: When one is walking in an unclean place, he may place his hand over his mouth and recite the Shema.
Rav Chisda said to him: My God—if Rabbi Yochanan himself said this to me I would not listen!”
The Hagahot Maimoniot and the Kessef Mishneh both explain that in this case, the Rambam supports the position of Rav Chisda over that of Rav Huna (as opposed to Halachot 12 and 13), because many other sages of the Gemara also accept the opinion of Rav Chisda.

For this is an odor that does not emanate from a solid substance as first mentioned in Halachah 12. The Hebrew word באשה is based on Joel 2:20.

Berachot 25a equates the two.

Rashi (Berachot 25a) explains the distinction between Kri’at Shema and Torah study as follows: One may leave the room and continue reciting the Shema. Therefore, one is obligated to stop if he remains. In contrast, a person studying Torah needs his books and therefore, cannot continue studying if he leaves the room. Accordingly, he need not interrupt his studies. This also explains the distinction between his own flatulence and that of a colleague. In the case of his flatulence, a person may leave for a moment and then return, but as the Shulchan Aruch, Orach Chayim 79:9 explains, we will not obligate a whole study hall to stop studying because of the flatulence of a few. The Shulchan Aruch HaRav (Orach Chayim 79:11) adds that this is considered as a factor beyond one’s control, and, therefore, does not require the interruption of study. This is based on the general rule that an odor that does not emanate from a visible substance does not lead to any restrictions according to Scriptural Law.
The Magen Avraham (79:15) mentions that perhaps, if a person was studying alone and could leave the room in order to avoid the foul odor, he should do so. The Shulchan Aruch HaRav, however, makes no such distinction and also allows one to continue studying.

Rashi (Berachot 25a) explains that it is not a normal practice to leave such materials in a house. Therefore, we may assume that the house is clean.

This applies to a garbage heap that has no foul smell of its own, but a doubt arises regarding the presence, or lack of, of feces (Rabbenu Manoach).

The Torah forbids reciting holy matters only in the presence of urine while it is actually being expelled from the person. The Rabbis added an injunction prohibiting the recitation of the Shema in the presence of urine even after its discharge. However, a doubt regarding such urine would produce a lenient halachic ruling, based on the principle ספק דרבנן לקולא—a doubt in a Rabbinic law produces a lenient response.

The previous halachot in this chapter have dealt with the prohibition of reciting the Shema in the presence of unclean substances and foul odors. As mentioned, this is a Torah prohibition based on the verse (Deuteronomy 23:15): “And your camp must be holy.”
The succeeding words in that verse—ולא יראה בך ערות דבר—“Let Him not see any nakedness among you” serve as the basis for halachot that follow in this chapter. These halachot deal with the impropriety of reciting the Shema in the presence of human nakedness.

Since the prohibition is based on the idea of לא יראה בך (lit., “It shall not be seen to you”), sight, and not physical distance, is of primary importance.

See Berachot 25b. The Torah Temimah explains that this prohibition even applies regarding the nakedness of primitive peoples who carry on their daily affairs unclothed.

The Rama (Orach Chayim 75:4) mentions that until the age of 3 for a girl and 9 for a boy, the Shema may be recited in their presence if they are naked. However, other opinions are not that lenient and forbid recitation of holy words even in the presence of the nakedness of small children. See Kitzur Shulchan Aruch 5:15.

Berachot 25b distinguishes between feces behind a glass partition, which is permitted (see Halachah 10) and nakedness, which is forbidden. Regarding feces, the Torah demands (Deuteronomy 23:14): “And you shall cover your excrement,” and a glass partition fulfills this function. However, the prohibition regarding nakedness is one of sight: לא יראה בך (“It shall not be seen to you”), and one sees through glass perfectly.

That is usually covered.

With whom he is familiar, how much more so other women.

Berachot 24a relates:
Rav Yitzchak says: A tefach (handbreadth) of a woman is ervah (nakedness).
With regard to what? With regard to gazing at it. Behold, Rav Sheshet says that anyone who stares even at the
little finger of a woman is like one staring at her most private parts. Rather, it refers to his wife and to Kri’at
Shema.
Rashi interprets this to mean that a man may not recite the Shema next to his wife if a handbreadth of her body is uncovered. Rabbenu Asher explains that this refers to any part of his wife’s body that is usually covered and clothed.
Berachot also mentions a woman’s hair and her voice as ervah. The Lechem Mishneh interprets this passage to mean that since these restrictions were established with respect to one’s wife, any part of the body of a woman other than his wife would be problematic. Thus, the Shema should not be recited in her presence.
The Shulchan Aruch, Orach Chayim 75:1 does not distinguish between a man’s wife and another woman and forbids the recitation of the Shema if a handbreadth of their body which is usually covered is uncovered. However, the Rama mentions the opinon that even less than a handbreadth of the body of a woman other than one’s wife is considered as “nakedness.”

This is based on the concept that one’s heart should not see his nakedness. This same principle is expressed in Chapter 2, Halachah 7.

For a man, this means covering his genitalia.

Though some of these portions of the body are normally covered, they are not considered as “nakedness.”

I.e., when he is sitting with his feet tucked under himself.
Berachot 25b reports a disagreement as to whether a heel may “see” or touch ערוה, and rules that though the heel may see ערוה, it cannot touch it. The rationale for this distinction is that the Torah was not given to angels. Rashi explains that this implies that we cannot be expected to maintain such a formidable level of care, because we were created with physical nakedness against our will.
Rabbenu Asher and Rabbenu Yonah suggest that no part of the body may touch one’s genitalia during Kri’at Shema, and that the heel is given only as an example. The Shulchan Aruch, Orach Chayim 74:5 accepts this position.

Between his heart and his genitalia.

Berachot 24b relates: “One who is lying under his sheet and is unable to stick out his head because of the cold should separate himself by placing his sheet under his neck, and recite [the Shema]; there are those that say on his heart.” The Rambam and the vast majority of Rishonim follow the second opinion, because the first opinion does not take into account the rule “One’s heart shall not see his nakedness.” If one is sleeping without clothes, he may separate the top half of his body from the lower half.

Without clothing.

And thus, his heart does not see his own nakedness.

Berachot 24a records a difference of opinion between Rav Yosef and Shmuel. Both agree (as the Rambam states later in this halachah) that when sleeping in the same bed with his wife, one need only turn his face away from her in order to recite the Shema. However, Shmuel is of the opinion that this same halachah applies even if he were sleeping with a person other than his wife, while Rav Yosef feels that this dispensation is only granted in regard to one’s wife.
Rashi explains the latter opinion as follows: Since a person is accustomed to being with his wife, lying with her will not prevent him from having proper intention while reciting the Shema. In contrast, when he lies with a person other than his wife, he must separate his body from that person’s, lest the touching of their bodies distract him.
It is interesting to note that there is a clear dispute between the great rabbis of Spain and North Africa (Rabbenu Yitzchak Alfasi, the Rambam and their disciples) and the great rabbis of Germany and France (Tosafot, Rabbenu Asher, and their disciples) concerning this halachah.
The Rabbis of France rule that one must make a separation with the sheet before reciting the Shema when sleeping in the same bed as one’s wife. Rav Yitzchak explains that the halachah is not according to either Shmuel or Rav Yosef and it is reasonable to be particularly strict based on a beraita
quoted in the Berachot 24a. In contrast, the Rabbis of Spain follow the Rambam’s view.
Generally, in such instances, the Shulchan Aruch will rule in accordance with the Rabbis of Spain, and the Rama with the Rabbis of France. In this instance, the Shulchan Aruch, Orach Chayim 73:2, after quoting both positions, suggests that it is fitting to follow the ruling of the Rabbis of France.

In contrast, bodily contact above this point would not induce sexual thoughts.
The Mishnah Berurah (Orach Chayim 73:1) points out, regarding this halachah, that were one to separate himself from another with the sheet, he need not also turn his head away.

See the following halachah for a definition of this term.

I.e., he is familiar with them and sexual thoughts are not likely to be aroused.

The Magen Avraham 73:1 requires a person to turn away his whole body so that only the back of his body is touching them, lest he be bothered by sexual thoughts if the front of his body touches them.

So that his heart will not see his own nakedness.

Rashi (Berachot 24a) explains that these are the ages when puberty begins, and from this time onward, the youths become physically attractive. However, this opinion does not place any conditions on that age. The Rambam adds a further point, making the age requirement conditional on the youth’s physical development.

Based on Ezekiel 16:7, Niddah 6:1 mentions these as signs of a woman’s physical maturity. See also Hilchot Ishut, Chapter 2.
From this time onwards, he may not recite the Shema unless he has first separated himself from them with the sheet, as mentioned in the first clause of the previous halachah.

As mentioned in the second clause of the previous halachah.

At this point they are considered adults, even if they do not have the physical characteristics of adulthood. Rabbenu Asher quotes and supports the position of the Rambam.