Talmud Bavli, Sotah
Sotah 40a
The Gemara records the dispute about what the congregation says while the shaliach tzibbur recites Modim. It presents the version known as 'Modim deRabbanan,' a composite of multiple rabbinic formulations including those of Rav, Shmuel, R' Simai, R' Yochanan, and others, each contributing a phrase to what became the standard congregational Modim.
בִּזְמַן שֶׁשְּׁלִיחַ צִבּוּר אוֹמֵר מוֹדִים, הָעָם מָה הֵם אוֹמְרִים? אָמַר רַב: ״מוֹדִים אֲנַחְנוּ לָךְ ה׳ אֱלֹהֵינוּ עַל שֶׁאָנוּ מוֹדִים לָךְ״. וּשְׁמוּאֵל אָמַר: ״אֱלֹהֵי כׇּל בָּשָׂר, עַל שֶׁאָנוּ מוֹדִים לָךְ״. רַבִּי סִימַאי אוֹמֵר: ״יוֹצְרֵנוּ יוֹצֵר בְּרֵאשִׁית עַל שֶׁאָנוּ מוֹדִים לָךְ״. נְהַרְדָּעֵי אָמְרִי מִשְּׁמֵיהּ דְּרַבִּי סִימַאי: ״בְּרָכוֹת וְהוֹדָאוֹת לְשִׁמְךָ הַגָּדוֹל עַל שֶׁהֶחֱיִיתָנוּ וְקִיַּימְתָּנוּ, עַל שֶׁאָנוּ מוֹדִים לָךְ״. רַב אַחָא בַּר יַעֲקֹב מְסַיֵּים בַּהּ הָכִי: ״כֵּן תְּחַיֵּינוּ וּתְחׇנֵּנוּ, וּתְקַבְּצֵנוּ, וְתֶאֱסוֹף גָּלִיּוֹתֵינוּ לְחַצְרוֹת קׇדְשֶׁךָ, לִשְׁמוֹר חוּקֶּיךָ וְלַעֲשׂוֹת רְצוֹנְךָ בְּלֵבָב שָׁלֵם, עַל שֶׁאָנוּ מוֹדִים לָךְ״. אָמַר רַב פָּפָּא: הִילְכָּךְ נֵימְרִינְהוּ לְכוּלְּהוּ.
§ The Gemara returns to discuss the response of the congregants to certain parts of the prayer service. While the prayer leader is reciting the blessing of: We give thanks, what do the people say? Rav says that they say: We give thanks to You, Lord our God, for the merit of giving thanks to You. And Shmuel says that one should say: God of all living flesh, for the merit of giving thanks to You. Rabbi Simai says that one should say: Our Creator, Who created everything in the beginning, for the merit of giving thanks to You. The Sages of Neharde’a say in the name of Rabbi Simai that one should say: We offer blessings and praises to Your great name, for You have given us life and sustained us, for giving thanks to You. Rav Aḥa bar Ya’akov would finish the blessing as follows: So may You give us life, and show us favor, and collect us, and gather our exiles into Your sacred courtyards, in order to observe Your laws and to fulfill Your will wholeheartedly, for giving thanks to You. Rav Pappa said: These Sages each added a different element to the prayer. Therefore, we should combine them together and recite all of them.
Why it matters — This is the primary talmudic source establishing Modim deRabbanan — the congregation's own Modim recited while the chazzan repeats the Amidah.