Commentary for Avodah Zarah 76:16

ואיכא דאמרי בטלפחי דמיא כ"ע לא פליגי דאסיר כי פליגי בחיטי ושערי מר סבר גזרינן הא אטו הא ומר סבר לא גזרינן

There are those who say: When [the shetita] is made from lentils and water all agree that it is prohibited; they disagree when it is made from wheat or barley. [Shmuel's father and Levi] hold that we prohibit it out of fear [that being permitted with water people will drink it when it has been prepared with vinegar], whereas [Rav] held that we do not prohibit it.

Daf Shevui to Avodah Zarah