This sugya derives the structure and obligation of zimun and discusses how a group of diners join together in praising God after a meal. It also explores how the wording and response of zimun function as communal hoda'ah and praise.
תָּנוּ רַבָּנַן: מִנַּיִן לְבִרְכַּת הַמָּזוֹן מִן הַתּוֹרָה? — שֶׁנֶּאֱמַר: ״וְאָכַלְתָּ וְשָׂבָעְתָּ וּבֵרַכְתָּ״ — זוֹ בִּרְכַּת ״הַזָּן״, ״אֶת ה׳ אֱלֹהֶיךָ״ — זוֹ בִּרְכַּת הַזִּמּוּן, ״עַל הָאָרֶץ״ — זוֹ בִּרְכַּת הָאָרֶץ, ״הַטּוֹבָה״ — זוֹ ״בּוֹנֵה יְרוּשָׁלַיִם״, וְכֵן הוּא אוֹמֵר ״הָהָר הַטּוֹב הַזֶּה וְהַלְּבָנוֹן״. ״אֲשֶׁר נָתַן לָךְ״ — זוֹ ״הַטּוֹב וְהַמֵּטִיב״. אֵין לִי אֶלָּא לְאַחֲרָיו, לְפָנָיו מִנַּיִן? — אָמְרַתְּ קַל וָחוֹמֶר: כְּשֶׁהוּא שָׂבֵעַ מְבָרֵךְ, כְּשֶׁהוּא רָעֵב — לֹא כׇּל שֶׁכֵּן. רַבִּי אוֹמֵר [אֵינוֹ צָרִיךְ]: ״וְאָכַלְתָּ וְשָׂבָעְתָּ וּבֵרַכְתָּ״ — זוֹ בִּרְכַּת הַזָּן, אֲבָל בִּרְכַּת הַזִּמּוּן מִ״גַּדְּלוּ לַה׳ אִתִּי״ נָפְקָא. ״עַל הָאָרֶץ״ — זוֹ בִּרְכַּת הָאָרֶץ, ״הַטּוֹבָה״ — זוֹ ״בּוֹנֵה יְרוּשָׁלַיִם״, וְכֵן הוּא אוֹמֵר ״הָהָר הַטּוֹב הַזֶּה וְהַלְּבָנוֹן״. ״הַטּוֹב וְהַמֵּטִיב״ בְּיַבְנֶה תִּקְּנוּהָ. אֵין לִי אֶלָּא לְאַחֲרָיו, לְפָנָיו מִנַּיִן? תַּלְמוּד לוֹמַר: ״אֲשֶׁר נָתַן לָךְ״ — מִשֶּׁנָּתַן לָךְ.
The Sages taught in a Tosefta: From where is it derived that Grace after Meals is from the Torah? As it is stated: “And you shall eat and be satisfied, and you shall bless the Lord, your God, for the good land that He has given you” (Deuteronomy 8:10). The Gemara explains: And you shall bless, that is the blessing of: Who feeds all. The Lord, your God, that is the zimmun blessing in which God’s name is invoked. For the land, that is the blessing of the land; good, that is the blessing: Who builds Jerusalem, and it also says: “This good mountain and Lebanon” (Deuteronomy 3:25), which is interpreted homiletically as referring to Jerusalem and the Temple. That He gave you, that is: Who is good and does good. However, I only have a Torah source for blessings after eating, i.e., Grace after Meals. From where is it derived that one is obligated to recite blessings before eating? You said that it can be derived through an a fortiori inference: When one is satisfied, he is obligated to recite a blessing and thank God for food; when he is hungry, all the more so that he should recite a blessing to offer thanks for the food he will eat. Rabbi Yehuda HaNasi says: It is not necessary to interpret the verse this way; rather, it should be understood in a slightly different manner, as follows: “And you shall eat and be satisfied, and you shall bless,” that is the blessing of: Who feeds all; however, the zimmun blessing is derived from the verse: “Praise God with me and we will exalt His name together” (Psalms 34:3). He continues: For the land, that is the blessing of the land. Good, that is the blessing: Who builds Jerusalem, and it also says: This good mountain and Lebanon. They instituted the blessing: Who is good and does good, at Yavne and, as such, it has no biblical source. However, I only have a Torah source for blessings after eating, i.e., Grace after Meals. From where is it derived that one is obligated to recite blessings before eating? The verse states: That he gave you. A blessing must be recited over food from the moment that God gave it to you, not only afterward.