It is a positive commandment from the Torah - Sefer Hamitzvot (Positive Commandment 170) and Sefer Hachinuch (Mitzvah 405) count this mitzvah as one of the 613 mitzvot of the Torah.

to hear the sounding of the shofar - The mitzvah is not the blowing of the shofar, as might be inferred from the verse, but rather listening to the blowing. The blessing recited before the fulfillment of this mitzvah, praising God for commanding us "to listen to the sounding of the shofar (Chapter 3, Halachah 10)," emphasizes this principle.

Accordingly, the Rambam writes (Chapter 1, Halachah 8) that a person who blows a shofar without hearing it does not fulfill the mitzvah. Conversely, he writes (Responsum 78) that if the mitzvah were the blowing of the shofar, a person who heard it being blown, but did not blow it himself, would not fulfill his obligation.

It must be noted that the published text of the siddur of Rav Amram Gaon states that the mitzvah is "to sound the shofar." Also, concerning the blowing of the shofar in the yovel, the Rambam himself writes that: "it is a positive mitzvah to blow the shofar on the tenth of Tishre... (Hilchot Shemitah V'Yovel 10:10)."

on Rosh HaShanah, as [Numbers 29:1] states: "It shall be a day of sounding [the ram's horn] for you." - Though the ram's horn is not explicitly mentioned in the verse, our Sages derived the requirement as the Rambam explains.

The shofar, which is sounded both on Rosh HaShanah and for the yovel - to announce the freeing of the slaves and the return of property, as explained in Leviticus 25:9-13.

is a bent -Rams' horns are always bent. This, too, has homiletic significance, referring to the bending over of our proud hearts. (See Rosh HaShanah 26b.)

ram's horn. - Rosh HaShanah 16a states that a ram's horn is used to recall the akedah (binding) of Isaac.

All shofarot other than that of a ram are unacceptable. - The Rambam's opinion is based on the statement of Rav Levi (Rosh Hashanah 26b), who declares: "The mitzvah of Rosh Hashanah is to be performed with bent [shofarot]," implying the use of a sheep's or ram's horn for that is their natural shape.

The Ra'avad, Rabbenu Asher, and many other Rishonim maintain that Rav Levi desired to designate the type of shofar which is most preferable to use, but did not intend to disqualify the horns of other animals. Their view is accepted by the Shulchan Aruch (Orach Chayim 586:1), which states that it is desirable to use the horn of a ram. However, if that is not possible, the horn of any animal may be used. The only exceptions are the horns of a cow and some wild animals whose horns are single, solid entities (Ramban).

Even though the sounding of the shofar on Rosh HaShanah - The above verse merely mentions יום תרועה - "a day of sounding" - without stating what must be sounded.

is not explicitly mentioned in the Torah [it was derived by our Sages in the following manner]. Concerning the yovel, [Leviticus 25:9] states: "You shall make a proclamation, sounding the shofar...you shall proclaim with the shofar." The oral tradition - Rosh Hashanah 33b

explains that just as the "sounding" required by the Torah in the yovel requires a shofar, so, too, the "sounding" on Rosh HaShanah requires a shofar. - An analogy (גזרה שוה) is drawn between the two verses, to teach that the same type of "sounding" is required on both occasions. Thus, since the Torah specifies states that the "sounding" of the yovel is carried out with a shofar, that same instrument is used on Rosh HaShanah.

In the Temple - As will be explained in the commentary to Chapter 2, Halachah 8, and Chapter 7, Halachah 13, in certain contexts the Rambam interprets the expression במקדש - literally, "in the holy place" - as referring to the entire city of Jerusalem. (See also the Rambam's commentary to the mishnah, Rosh HaShanah 4:1.) However, in the present context, it refers to the Temple alone. Thus, Rosh HaShanah 27a states that the shofar was sounded in this manner only "on the Temple Mount and at the eastern gate."

on Rosh HaShanah, they would blow [the shofar in the following manner]: There was one shofar and two trumpets, [one on either] side. - The verse from Psalms mentions "the voice of the shofar," using the singular. In contrast, it refers to "trumpets."

The sounding of the shofar was extended - for greater emphasis

while that of the trumpets was shortened, because the mitzvah of the day is performed with the shofar. - Rosh HaShanah 26b contrasts the sounding of the shofar and trumpets on Rosh HaShanah with their being blown on a fast day declared because of unfavorable conditions. On the latter occasion, the sounding of the trumpets was emphasized in keeping with the instructions of Numbers 10:9.

Why were the trumpets sounded together with it? Because [Psalms 98:6] states: "You shall sound trumpets and the voice of the shofar before God, the King." - Rosh Hashanah 27a states that the expression "before God" implies: in the Temple.

However, in other places - even within Jerusalem

on Rosh Hashanah, only the shofar is blown.

At the outset, we should not blow a shofar of idol worship. - For it is not appropriate to use such a shofar for a mitzvah.

However, if one sounded it, one has fulfilled his obligation. - The Maggid Mishneh explains that this refers to a shofar belonging to a gentile that was used in the worship of idols, or a shofar which was itself worshiped as an idol. However, as will be explained, if the shofar of idol worship belonged to a Jew or if it was made from the horn of an animal that was sacrificed to an idol, even after the fact, its use is not acceptable.

[In contrast,] should one sound a shofar belonging to an apostate city, - עיר הנדחת. Deuteronomy 13:13-19 describes the laws governing a city in which the majority of the inhabitants have turned to idol worship. All the idolaters must be slain and all the homes and property burned. No benefit may be derived from them. (See also Hilchot Avodat Kochavim, Chapter 4.)

one has not fulfilled one's obligation. - Rosh Hashanah 28a explains that the difference between a shofar of idol worship and one of an apostate city is that all the property within the latter must be destroyed. Since ultimately this shofar must be burnt, even before it is actually destroyed it is no longer considered to be an existent entity. Thus, we may not use it on Rosh HaShanah, because a shofar used for the mitzvah must be of a specific size - slightly larger than one's hand, as mentioned in Halachah 5 - and a nonexistent entity has no size at all.

A shofar of idol worship must also be destroyed. However, should the gentile negate its connection to idol worship before it is acquired by a Jew, it need not be destroyed, as stated in Hilchot Avodat Kochavim 8:8. Since there is a possibility that it will not have to be destroyed, it is considered to be an existent entity and may be used for the mitzvah.

This principle applies only to aspects of idol worship belonging to a gentile. It is impossible to negate the connection between an idol worshiped by a Jew and its forbidden nature. (See Hilchot Avodat Kochavim 8:9.) Hence, a Jew's shofar of idol worship may not be used. Similarly, if a Jew has acquired a shofar of idol worship that belonged to a gentile before the latter negated its connection to idol worship, the Jew is no longer capable of negating this connection. Therefore, such a shofar may not be used on Rosh HaShanah.

Also, once an animal has been sacrificed to an idol, there is no possibility of negating its connection to idol worship. Hence, its horn may not be used as a shofar.

The Shulchan Aruch (Orach Chayim 586:3-4) quotes all the above laws as halachah. The Ramah relates that certain authorities recommend not using even a gentile's shofar of idol worship unless we know that he negated its connection with idol worship before Rosh HaShanah begins.

Concerning a stolen shofar - one who blows it fulfills his obligation - Though in general, a mitzvah performed with a stolen article is not acceptable (see Chapter 8, Halachah 1; Hilchot Chametz U'Matzah 6:7), this case is an exception...

because the mitzvah is only to listen to the sound - Hence, a person who listens to the shofar being blown fulfills his obligation

even though the listener does not touch [the shofar] - Based on this statement, the commentaries propose that, according to the Rambam, a person who blows a shofar without putting his lips to it fulfills his obligation. The Ramban (see Maggid Mishneh 1:6) does not accept this view.

or lift it up. - Accordingly, after the fact, by hearing such a shofar, one has fulfilled one's obligation, because

The laws of theft do not apply to sound alone - for sound is not a physical entity that can be possessed. Rabbenu Manoach and the Kessef Mishneh cite other examples from Nedarim 13b-15a, where the Sages differentiate between sound and material entities.

The Jerusalem Talmud (Sukkah 3:1) derives this law as follows:

Everyone agrees that a stolen lulav is unacceptable. What is the difference between a shofar and a lulav?

Rabbi Yosse responded: "Concerning a lulav, [Leviticus 23:40] states: 'You shall take for yourself,' implying that only 'your own' is acceptable. In contrast, [Numbers 29:1] states: 'It shall be a day of blowing for you,' implying that regardless [of the nature of the shofar used, the blowing shall be 'for you']".

Rabbi Eliezer explained: "There, [concerning the lulav,] one must perform the mitzvah with the lulav itself. Here, [concerning the shofar,] one performs the mitzvah with its sound."

Nevertheless, because a sin is associated with this mitzvah, Ashkenazic custom is that no blessing should be recited before blowing such a shofar (Magen Avraham 586:4).

Similarly, a shofar from an - animal consecrated as an...

olah offering should not be sounded, - Once an animal is consecrated as an olah offering, no part of its body may be used any other purpose. Therefore, we should not use such a shofar from such an animal for any purpose whatsoever.

This halachah applies before the blood from the sacrifice has been offered on the altar. Afterwards, the skin and horns of the animal become the property of the priests and may be used for mundane purposes (Rashi, Rosh Hashanah 28a).

but if one sounds it, he fulfills his obligation, because the laws of מעילה - The prohibitions forbidding use of consecrated articles for mundane purposes...

do not apply concerning sound alone. - In Hilchot Me'ilah 5:16, the Rambam writes:

Concerning the sound, sight, and smell of consecrated objects: We should not derive benefit from them. However, all the implications of the prohibition against using them for mundane purposes do not apply.

If you ask: "Behold, he has derived benefit from hearing [the shofar's] sound?" - Though the laws of מעילה do not apply to sound, there is still a Rabbinic prohibition against benefiting from the sound of consecrated articles. Therefore, one might think that we would be unable to fulfill the mitzvah with such a shofar (Lechem Mishneh). Accordingly, the Rambam explains:

Mitzvot were not given for our benefit - Rashi (Rosh Hashanah, ibid.) states: "the mitzvot were not given to the Jewish people for their enjoyment, but rather as a yoke."

This concept has relevance in the ethical, as well as the halachic sphere. In the tenth chapter of Hilchot Teshuvah, the Rambam writes:

One who serves [God] out of love occupies himself with the Torah and the mitzvot...for no ulterior motive, not because of fear that evil will occur, nor in order to acquire benefit...

The great Sages would command the more understanding and brilliant among their students in private: "Do not be like servants who serve their master for the sake of receiving a gift. Rather, since he is the Master, it is fitting to serve Him"; i.e., serve [Him] out of love.

The above is not intended to imply that a person should not feel happy and fulfilled in the service of God. Quite the contrary; indeed, the Rambam concludes these halachot (Chapter 8, Halachah 15) with a description of the importance of happiness in the service of God. However, the intent is that the happiness should be a byproduct and not the goal of the service. We should be totally committed to fulfilling God's will, and the expression of that commitment should generate satisfaction and joy.

Based on this concept - that mitzvot were not given for our benefit;

a person who vows not to derive benefit from a shofar may use it to blow the teki'ot required to fulfill the mitzvah. - Doing so is not considered a violation of his vow.

The Shulchan Aruch (Orach Chayim 586:5) advises that the person who took the vow should not blow the shofar himself [because many consider that to be a pleasurable experience (Taz)]. Rather, he should hear the teki'ot from a colleague.

Also, the Shulchan Aruch (ibid.) notes that if a person specifically states that he vows not to listen to a colleague's teki'ot, he may not hear that person blow the shofar on Rosh HaShanah, because a vow (neder) can also negate a mitzvah. (See Hilchot Nedarim 3:6-8.)

Regarding a shofar to be used on Rosh HaShanah: It is forbidden to violate the festival laws to obtain it. This applies - not only when obtaining the shofar requires the violation of a melachah (forbidden labor) prohibited by the Torah, but

even when the forbidden practice is in the category of sh'vut. - In Hilchot Shabbat 21:1, the Rambam defines sh'vut as a prohibition instituted by the Sages because a particular activity resembles one forbidden as a melachah by Torah law, or because performing it may cause one to perform a melachah.

Though these prohibitions are of Rabbinic origin, the Sages reinforced the power of their decrees and equated them with Torah law. Hence, just as one may not violate a melachah forbidden by the Torah to obtain a shofar, so, too, it is forbidden to violate a sh'vut forbidden by Rabbinic law (Kessef Mishneh). [Nevertheless, note the clarification of this principle in Chapter 2, Halachah 6.]

How is the above exemplified? If there is a shofar in a treetop or across a river - and that is the only shofar available - one may not climb the tree - lest one accidentally cut off a branch (ibid., 6)

or swim across the water to bring it - lest one prepare a swimming aid (ibid., 23:5). The Mishnah (Rosh Hashanah 32b) mentions other examples of forbidden activities.

Needless to say, we may not cut the shofar [from the animal's head] - In his commentary on the mishnah, the Rambam explains that this refers to cutting the horn off with a household knife. Since a craftsman's knife is not being used, cutting the shofar off is not forbidden by Torah law. Nevertheless, the Rambam uses the expression "needless to say," because such an activity bears a closer resemblance to one forbidden by Torah law than those mentioned previously.

or perform a forbidden labor - cutting off the horn with a craftsman's knife

[to prepare a shofar so that we may blow it].

[The rationale for the above is:] Blowing the shofar fulfills a positive commandment - as stated in Halachah 1.

while [the observance of] the festivals fulfills both a positive and a negative commandment. - In Hilchot Sh'vitat Yom Tov 1:2, the Rambam writes:

Whoever rests from a melachah categorized as "work" on one of [these days] fulfills a positive commandment, because the Torah describes them as "days of rest"... if one performs a melachah that is not intended to prepare food,... one negates the performance of a positive commandment and transgresses a negative commandment, as [Leviticus 23:8] states: "You shall not perform any servile work."

The observance of a positive commandment does not negate the observance of both a positive and negative commandment. - Though the performance of a positive commandment overrides a negative commandment (Yevamot 3b), that applies only when the negative commandment is not reinforced by a positive commandment, as in the case at hand.

It is permitted to rinse a shofar with water, wine, or vinegar in order to improve its tone. - It is forbidden to prepare a utensil for use on a festival. (See Hilchot Sh'vitat Yom Tov 4:8.) However, this activity is not placed in that category (Rabbenu Manoach).

However, as an expression of deference, one should never - i.e., even before Rosh HaShanah

use urine [for that purpose], lest one view the mitzvot in a deprecating manner. - The Rambam concludes Hilchot Shechitah (14:16):

...lest one view the mitzvot in a deprecating manner, because the deference is not to be granted to the mitzvot in and of themselves, but to the One who commanded us to fulfill them, blessed be He.

The minimum size of a shofar is [a measure] sufficient that one may hold the shofar in one's hands [with the ends] visibly [protruding] - The protrusions are necessary lest one say that a person is producing the sounds by blowing into his hands without a shofar.

on either side. - Niddah 26a defines this measure as "an expanded handbreadth." The Beit Yosef notes that, in this context, a handbreadth is defined as four thumbbreadths. Thus, the difference between the width of a thumb and the other fingers accounts for the "expansion." In modern measure, a handbreadth is considered between 8 (Shiurei Torah) and 9.6 (Chazon Ish) centimeters.

Should a shofar be cracked lengthwise - i.e., from its mouth to its end;

it is unacceptable. - This is a quote from Rosh Hashanah 27b. The Rabbis have noted that, in contrast to a crack along the shofar's width, in this context no minimum figure is mentioned with regard to the portion of the shofar remaining uncracked. Two contrasting interpretations are offered to explain the difference.

Some maintain that as long as the entire length (or the majority of the length) of the shofar is not cracked, the shofar is not disqualified. Others maintain that even the slightest crack along the length of the shofar disqualifies it, because the pressure of the blowing will cause the crack to grow until, ultimately, the entire shofar will be cracked (Rabbenu Asher; Shulchan Aruch, Orach Chayim 586:8).

Concerning halachah l'ma'aseh, both the Shulchan Aruch HaRav (586:8) and the Mishnah Berurah (586:43) write that when no other shofar is available, one may rely on the first opinion. Nevertheless, even the latter opinion does not disqualify a shofar that is cracked lengthwise if it is tied firmly so that the crack will not expand, or if the shofar is heated and the crack closed. Some opinions also allow such a shofar to be used if the crack is plugged closed with other substances.

Should it be cracked along its width - with the crack extending along the majority of the shofar's circumference (Shulchan Aruch, Orach Chayim ibid., 9),

if a measure equivalent to the minimum size of a shofar remains - Most authorities require a handbreadth to remain from the crack to the shofar's mouth (Kessef Mishneh). However, the Ba'al Ha'itur maintains that a shofar is acceptable even if the minimum measure remains only from the crack to the end of the shofar.

it is kosher. - This applies even if the sound of the shofar is changed because of the crack (Shulchan Aruch, ibid.).

It is considered as if it were cut off at the place of the crack. - Hence, the crack does not disqualify it.

[Regarding a shofar with] a hole: If it was plugged - In his commentary on the Mishnah (Rosh Hashanah 3:5), the Rambam writes that the hole must be plugged. This point is not accepted by the Shulchan Aruch (ibid., 7), which emphasizes that if the hole is not plugged, the shofar is kosher even though its sound has changed. Nevertheless, the Ramah states that if another shofar is available, a shofar with a hole should not be used.

with another substance, - i.e., any substance other than a ram's horn;

it is unacceptable - because the sound produced does not come from the shofar alone, but rather from the shofar and the other substance.

If;

a) it was plugged with its own kind,

it is kosher [under the following conditions]:

b) the majority of the shofar remained whole;

c) the plugging of the holes did not alter its sound. - These three conditions are dependent on the Rambam's interpretation of Rosh Hashanah 27b. Rabbenu Asher interprets the passage differently. The Shulchan Aruch (ibid.) favors the Rambam's interpretation, but states that under difficult circumstances, when no other shofar is available, one may rely on Rabbenu Asher's interpretation.

If one [merely] perforated the insides of the horn, - the bonelike tissue inside the horn

[but did not remove them,] it is kosher, because a substance of the same kind is not considered an intervening entity. - The presence of a foreign substance inside the shofar would cause it to be disqualified, as stated in the following halachah. However, since this tissue is considered to be part of the horn itself, the shofar is acceptable.

The Shulchan Aruch (ibid., 586:15) quotes this law, but also adds that if one removed this tissue from the horn and then hollowed it out, the tissue would be unacceptable for use as a shofar.

Should one stick together fragments of shofarot until one has constructed a shofar, it is unacceptable. - Tosafot, Rosh Hashanah 27a explains that this construction is not called a shofar. The Shulchan Aruch (ibid., 10) states that this law applies even if the fragment of the shofar closest to one's mouth is of sufficient size to be considered a kosher shofar itself.

If one made any addition to a shofar - whether from the mouthpiece or from the wider end (Shulchan Aruch HaRav 586:11).

whether of its kind - using a fragment of a ram's horn

or from another substance - it is unacceptable. - On the surface, this law appears to be an extension of the principle mentioned in the last clause of the previous halachah. If so, one might question why the Rambam mentions them in two separate halachot.

Should one coat it with gold - or any other foreign substance

from the inside or at the mouthpiece, it is unacceptable - for the sound must come from the shofar itself. Though Rosh Hashanah 26b mentions that the mouth of the shofar used in the Temple was coated with gold, the place where the person blowing would put his mouth was not covered.

Should one coat it - with gold or any other substance

on the outside: If its sound is changed from what it was originally, it is not acceptable - for then, the sound we hear is a product of both the shofar and the coating, and not the shofar alone.

Based on this law, the Ramban advises against making designs in the shofar and coating them with paint or metal, for this may alter the shofar's sound and prevent the teki'ot from being acceptable.

If its sound did not change, it is kosher - All these laws are quoted by the Shulchan Aruch (Orach Chayim 586:16).

Should one place one shofar within another: If one hears the sound of the inner shofar, - i.e., with the further end of the inner shofar protruding beyond that of the outer shofar

one has fulfilled one's obligation - for the outer shofar had no effect on the sound we hear. The Shulchan Aruch (Orach Chayim 586:20) emphasizes that one may fulfill one's obligation under such circumstances only if the sound of the inner shofar remains totally unchanged. The teki'ot are unacceptable if its sound is altered.

If one hears the outer shofar - i.e., its edge protrudes beyond that of the inner shofar

one has not fulfilled one's obligation - for then, one is hearing the sound of two shofarot. The Torah commanded us to hear one shofar and not two (Tosafot, Rosh Hashanah 27b).

Should one widen the narrow portion of the shofar and narrow its wider end, the shofar is unacceptable. - Rosh Hashanah 27b explains the derivation of this law as follows: The terminology which Leviticus 25:9 uses when commanding us to blow the shofar, שופר והעברת, has an additional implication. That expression is also related to the word עבר, meaning "to pass." The manner in which we use the shofar must parallel the manner in which the ram passes by with it on its head.

Based on the same principle, our Sages (ibid.) explain that a shofar is unacceptable if it was heated to the point that the horn became soft, and then turned inside out.

If a shofar was long and one shortened it - It makes no difference whether the portion is cut away from the shofar's mouthpiece or from its wider portion (Mishnah Berurah 586:63).

it is kosher. - Tosafot, Rosh Hashanah 27b explains that the necessity of mentioning this law arises from the last clause of the previous halachah. Since we find that the Torah requires us to use the shofar in the same manner as which it was carried by the ram, a special teaching is necessary to inform us that a shofar is acceptable even if it was shortened.

The Kessef Mishneh explains that such a shofar is acceptable even it was shortened because of a disqualifying factor which it possessed on the portion which was cut off.

If one scraped away the horn - either from the inside - widening the hollow of the shofar

or from the outside - scraping away its outer shell

even if one did so to the extent that all that remained was the thin external shell, - even if the sound of the shofar changes (Shulchan Aruch HaRav 586:13; Mishnah Berurah 586:65).

it is kosher - since no change is made in its fundamental shape.

Regardless of whether [the shofar's] sound is heavy, thin, or raspy, - Rabbenu Manoach and the Kessef Mishneh translate צרור as "dry," explaining that blowing a shofar causes it to dry out and produce a raspy tone. Hence, it was customary to rinse it with water or wine, as mentioned in Halachah 4.

it is kosher, because all the sounds produced by the shofar are kosher. - In his commentary on this clause, Rabbenu Manoach injects a spiritual concept emphasizing how the musical quality of the shofar's tones are not significant, but rather the stirring and rousing nature of the shofar's call which motivates the people to Teshuvah.

When a person sounds a shofar within a pit or within a cave - Rav Hai Gaon writes that these laws were not merely questions of abstract theory. Rather, they carried practical relevance in the Talmudic period, when the Jews frequently had to perform mitzvot clandestinely, to avoid being observed by the Roman authorities.

those standing within the pit or cave fulfill their obligation. - for they hear the shofar's sound alone. Needless to say, both they and the person blowing the shofar must fulfill the conditions outlined in Chapter 2 regarding a person's fulfillment of the mitzvah when hearing the shofar blown by a colleague.

Concerning those standing outside: If - all

they hear - is

the sound of the shofar, they fulfill their obligation. - However,

if they hear the sound of an echo - even if they hear the sound of the shofar together with it,

they do not fulfill their obligation - because another sound is mixed together with the desired sound.

Similar principles apply regarding one who blows into a giant barrel. If he hears - The Kessef Mishneh explains that the Rambam does not mention people standing within a barrel, because that is a very unlikely eventuality.

the sound of a shofar - alone,

he fulfills his obligation. If he hears an echo - together with the shofar,

he does not fulfill his obligation. - The Taz 587:1 explains that this concept is also relevant for synagogues with poor acoustics. If the people hear echoes together with the shofar's sound, they do not fulfill their obligation.

At present, there is a more common application of this principle. A person who hears the shofar through a microphone does not fulfill the mitzvah. In addition to the difficulties involved with the use of the microphone on a festival, there is a more essential problem. The listeners are not hearing the sound of the shofar, but rather a second sound, produced by a different mechanism. The microphone converts the sound waves of the shofar to electronic signals; these are then amplified and converted to a different set of sound waves. Hence, by hearing such a sound, we cannot fulfill the mitzvah obligating us to hear a shofar's call.