Talmud Bavli, Sotah
Sotah 40a
This is the primary source for Modim deRabbanan. The Gemara records that when the shaliach tzibbur (prayer leader) bows and says Modim, the congregation recites their own version of Modim. It then cites the different formulations offered by various Amoraim — Rav, Shmuel, R. Simai, R. Yochanan, and R. Papa — which were later combined into the text we use today.
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 foundational Talmudic source that establishes the practice of Modim deRabbanan and provides the raw texts that make up its content.