Megillah 23b
מגילה כ״ג ב — ד"ה מַתְנִי׳ אֵין פּוֹרְסִין עַל שְׁמַע
Megillah 23b:4
Lists matters that require ten and derives the principle of davar shebikdushah, the broader category under which Chazarat HaShatz is treated by the later halakhic authorities.
מַתְנִי׳ אֵין פּוֹרְסִין עַל שְׁמַע, וְאֵין עוֹבְרִין לִפְנֵי הַתֵּיבָה, וְאֵין נוֹשְׂאִין אֶת כַּפֵּיהֶם, וְאֵין קוֹרִין בְּתוֹרָה, וְאֵין מַפְטִירִין בַּנָּבִיא, גְּמָ׳ מְנָא הָנֵי מִילֵּי? אָמַר רַבִּי חִיָּיא בַּר אַבָּא אָמַר רַבִּי יוֹחָנָן, דְּאָמַר קְרָא: ״וְנִקְדַּשְׁתִּי בְּתוֹךְ בְּנֵי יִשְׂרָאֵל״, כׇּל דָּבָר שֶׁבִּקְדוּשָּׁה לֹא יְהֵא פָּחוֹת מֵעֲשָׂרָה.
MISHNA: One does not recite the introductory prayers and blessing [poresin] before Shema; nor does one pass before the ark to repeat the Amida prayer; nor do the priests lift their hands to recite the Priestly Benediction; nor is the Torah read in public; nor does one conclude with a reading from the Prophets [haftara] in the presence of fewer than ten men. GEMARA: The Gemara asks: From where are these matters, i.e., that ten people are needed in each of these cases, derived? Rabbi Ḥiyya bar Abba said that Rabbi Yoḥanan said: It is as the verse states: “And I shall be hallowed among the children of Israel” (Leviticus 22:32), which indicates that any expression of sanctity may not be recited in a quorum of fewer than ten men.