…They [Beit Shamai and Beit Hillel] came and even decreed [about] yichud.
Yichud was decreed by the court of David, as Rav Yehuda said “at that time they decreed about yichud!”
They say: There it [refers to] yichud of a Jewish woman, but not to yichud of an idolater. And they came and decreed even aboutyichud of an idolater.
[But] yichud of a Jewish woman is biblical…?!
Biblical yichud is of a married woman, and David came and decreed even about yichud of an unmarried woman,
and the students of the house of Shammai and the house of Hillel came and decreed even about yichud of an idolater.
[Babylonian Talmud Tractate Avodah Zarah 36b]
