Mishneh Torah (Rambam) משנה תורה

Women and slaves are obligated to recite grace. There is a doubt whether their obligation stems from the Torah, since [this is a positive mitzvah] that is not linked to a specific time, or whether their obligation does not stem from the Torah. Therefore, they should not fulfill the obligation of grace on behalf of others. Children, however, are obligated to recite grace by virtue of Rabbinic decree, in order to educate them to perform mitzvot.

When three people eat [a meal including] bread together, they are obligated to recite the blessing of zimmun before grace. What is the blessing of zimmun? If there were between three and ten participants in a meal, one recites the blessing, saying, "Let us bless Him of whose [bounty] we have eaten." Everyone responds: "Blessed be He of whose [bounty] we have eaten and by whose goodness we live." The one [reciting the blessing] then repeats: "Blessed be He of whose [bounty] we have eaten and by whose goodness we live."

Afterwards, he recites, "Blessed are You, God, our Lord, King of the universe, who sustains the entire world in His goodness..." until he completes the four blessings [of grace]. The others answer Amen after each blessing.

If ten or more people eat together, the zimmun should be recited with God's name. What is implied? The one reciting the blessing declares, "Let us bless to our God of whose [bounty] we have eaten." The others respond: "Blessed be our God of whose [bounty] we have eaten and by whose goodness we live." The one [reciting the blessing] then repeats: "Blessed be our God of whose [bounty] we have eaten and by whose goodness we live." He then begins reciting grace.

When eating in the home of a bridegroom from the time when the preparations for the wedding feast have begun until 30 days after the wedding, the one reciting the blessings should say, "Let us bless Him in whose abode is joy, of whose bounty we have eaten," and the others respond, "Blessed be He in whose abode is joy, of whose bounty we have eaten...." If ten people are present, he says, "Let us bless our God in whose abode is joy, of whose bounty we have eaten..." and the others respond, "Blessed be our God in whose abode is joy, of whose bounty we have eaten...." Similarly, whenever a feast is held because of the wedding for twelve months after the wedding, one should include the phrase, "in whose abode is joy."

All men are obligated in the blessing of the zimmun as they are obligated in grace, even priests who partook of sacrifices of the most sacred order in the Temple Courtyard. Similarly, priests and Israelites who ate together are required to recite the zimmun as they are required to recite grace, although the priests partook of terumah and the Israelites ordinary food.

Women, servants, and children are not included in a zimmun. They may, however, make a zimmun among themselves. Nevertheless, for the sake of modesty, there should not be a company that consists of women, servants, and children [together]. Instead, women may make a zimmun alone, as may servants and as may children. They should not, however, mention God's name. An androgynous may make a zimmun among his own kind, but should not be included among a zimmun either of men or of women. A tumtum should not be included in a zimmun at all. A child who understands Whom is being blessed may be included in a zimmun, although he is merely seven or eight years old. He may be counted among either a group of three or a group of ten for the purpose of zimmun. A gentile may not be included in a zimmun.

Only those who ate at least an amount of bread equal to the size of an olive should be included in a zimmun. When seven people partake of bread and three eat vegetables or brine and the like with them, the latter may be included in the zimmun, so that God's name may be mentioned, provided the one reciting the blessings partook of bread. In contrast, should six people partake of bread and four eat vegetables, the latter may not be included. There has to be a distinct majority of people who partook of bread. When does the above apply? With regard to [a zimmun of] ten. Regarding three, however, they should not recite the zimmun unless each one of them eats a portion of bread the size of an olive.

[The following rule applies when] two people eat together and complete their meal, and afterward, a third person comes and eats. If the others can eat any food [- they need not partake of bread -] together with him, he should be included [in the zimmun] with them. The sage of the greatest stature among those dining should recite grace, although he arrived at the end of the meal.

When three people eat together, they may not separate [and recite grace without a zimmun]. The same applies to four and five people. Between six and ten people may separate [and recite grace in two groups]. If more then ten people are present, they may not separate until [their number reaches] twenty. [The governing principle is that a group may separate only if] the blessing of the zimmun will be the same for both groups if they separate.

When three people who each came from a different group of three [join together], they should not separate [without reciting grace with a zimmun]. If each of them already participated in a zimmun, they may separate. They are not obligated to participate in a zimmun again, because a zimmun was already recited including them. When three people sit down [together] to eat bread, they may not separate even though each person eats from his own food.

[The following rules apply when] two groups eat together in the same building: When part of one group can see part of the other group, they may join together in a single zimmun. If not, they should each recite a zimmun separately. If there is a single attendant who serves both of these groups, they may join in a single zimmun, even though none of the people in the two groups see each other, provided both groups can clearly hear the words of the person reciting the blessings.

When three people ate together and one went out to the marketplace, he should be called to pay attention to what they are saying. He may be included in the zimmun while he is at the marketplace, and thus fulfill his obligation. Afterwards, when he returns to his house, he should recite grace alone. In contrast, when ten people eat together and one goes out to the market place, the zimmun may not be recited until he returns to his place.

When three people eat together and one recites grace alone before the others, the zimmun can be recited with him and the other two fulfill their obligation. He, however, is not considered to have fulfilled his obligation, because the zimmun cannot be fulfilled retroactively.

When two people eat together, each person should recite grace by himself. If one knows [how to recite grace] and the other does not, the one who knows should recite the grace out loud, and the other person should recite Amen after each blessing. In this manner, he fulfills his obligation. A son may recite grace for his father, a servant for his master, and a woman for her husband - and thus enable the person to fulfill his obligation. Nevertheless, our Sages said, "May a curse come on a person whose wife or children recite grace for him."

When do the statements that [it is possible to] fulfill one's obligation [in this manner] apply? When they have not eaten to the point of satiation. Therefore, their obligation is only Rabbinic in origin, and can be fulfilled by [listening to] a minor, a servant, or a woman. If, however, they ate to the point of satisfaction, and thus are obligated according to the Torah itself to recite grace, they cannot fulfill their obligation by [listening to] either a woman, a minor, or a servant. Anyone who is obligated according to the Torah to perform a mitzvah can have his obligation fulfilled only by another person who is also obligated from the Torah [to fulfill this mitzvah] as he is.

[The following rules apply when] a person enters [a room where] others are reciting the blessing of zimmun]: If he [enters when] the person reciting the blessings says, "Let us recite grace," he should respond, "Blessed is He, and may He be blessed." If he [enters when] the others reply, he should say Amen afterward.