Pesachim 51A

אי אתה רשאי להתירן בפניהם. אמר לו: ולאו מי איתמר עלה, אמר רב חסדא: בכותאי! כותאי מאי טעמא ⁠— משום דמסרכי מילתא, הנך אינשי נמי סרכי מילתא.

you are not allowed to permit these actions in their presence, lest they come to treat other prohibitions lightly, saying: If this previously prohibited activity was permitted, other prohibitions are not particularly stringent either. How did Rav Yosef permit the residents of Ḥozai to eat rice dough? Rav Yosef said to Abaye: And wasn’t it stated about this halakha concerning stringencies that Rav Ḥisda said: This was stated specifically with regard to Samaritans? The Talmud rejects this: What is the reason that this applies to Samaritans? It is due to the fact that they will extend this matter of leniency, and add to it additional, unjustified leniencies. These people of Ḥozai will also extend this matter of leniency, and come to practice additional leniencies in other cases, as they are commoners [amei ha'aretz].

אלא אמר רב אשי: חזינן אי רובן אורז אכלי ⁠— לא ניכלה זר באפייהו, דילמא משתכחא תורת חלה מינייהו. ואי רובן דגן אכלי ⁠— ניכלה זר באפייהו, דילמא אתי לאפרושי מן החיוב על הפטור, ומן הפטור על החיוב.

Rather, Rav Ashi said: We see, if the majority of people in that place eat rice, do not let a non-priest eat ḥalla in their presence, lest the halakhic category of ḥalla be forgotten from them. And if most of them eat grain, let a non-priest eat ḥalla separated from rice dough in their presence, lest they separate ḥalla from grain, from which separating ḥalla is a requirement, on behalf of rice from which separating ḥalla is an exemption, in which case the priest eating the ḥalla would be eating bread from which ḥalla was not separated; or from that which is an exemption on behalf of that which is a requirement, in which case the person eating the grain bread would be eating bread from which ḥalla was not separated.