Sanhedrin 74B

אפילו לשנויי ערקתא דמסאנא.

Even to change the strap of a sandal. There was a Jewish custom with regard to sandal straps. If the non-Jew authorities were to decree that Jews must change their practice and wear sandal straps like those worn by the non-Jews, one would be obligated to give up his life rather than veer from the accepted custom.

וכמה פרהסיא? אמר רבי יעקב אמר רבי יוחנן: אין פרהסיא פחותה מעשרה בני אדם. פשיטא, ישראלים בעינן, דכתיב: ״ונקדשתי בתוך בני ישראל״. בעי רבי ירמיה: תשעה ישראל וגוי אחד, מהו?

The Talmud asks: And the presence of how many people is required so that it should be deemed a public act? R' Ya’akov says that R' Yoḥanan says: An action is not considered a public act if it is performed in the presence of fewer than 10 people. The Talmud clarifies this point: It is obvious that we require that these 10 people be Jews, as it is written in the verse from which we derive the requirement of 10 for the sanctification of God’s name: “And I should be sanctified among the children of Israel” (Leviticus 22:32). R' Yirmeya asks: What is the halakha if there were 9 Jews and one non-Jew present?

תא שמע, דתני רב ינאי אחוה דרבי חייא בר אבא: אתיא ״תוך״ ״תוך״⁠ – כתיב הכא: ״ונקדשתי בתוך בני ישראל״, וכתיב התם: ״הבדלו מתוך העדה הזאת״. מה להלן עשרה וכולהו ישראל, אף כאן עשרה וכולהו ישראל.

The Talmud answers: Come and hear an answer from what Rav Yannai, the brother of R' Ḥiyya bar Abba, teaches in a baraita: This is derived by means of a verbal analogy between the word “among” written with regard to the sanctification of God’s name, and the word “among” written with regard to Korah and his assembly. Here, with regard to the sanctification of God’s name, it is written: “And I should be sanctified among the children of Israel,” and there, with regard to Korah, it is written: “Separate yourselves from among this congregation” (Numbers 16:21). The meaning of the word “congregation” written with regard to Korah is derived by means of a verbal analogy to the word “congregation” written with regard to the spies sent out by Moses to scout the land: “How long should I bear with this evil congregation” (Numbers 14:27). Just as there, the congregation of spies numbered 10, and all were Jews, so too here, concerning the sanctification of God, there must be 10, all of them being Jews.