רב חייא בר רב מדיפתא

Rav Chiyya bar Rav of Difti was an amora who was active in Bavel across the third, fourth and fifth generations of the Babylonian Amoraim. In most of the places where the Bavli mentions him it is as one who taught baraitot, and he taught them in the batei midrash of amoraim of different generations — before Rav Chisda, before Rav Bibi bar Abaye, and before Rav Papa. He is named together with his place, Difta or Difti, apparently in order to distinguish him from another amora of the same name, Chiya bar Rav.

Two of the baraitot he taught are among the well-known passages of Shas. On the verse in Shemot — that the people stood over Moshe from the morning until the evening — he taught that it cannot be that Moshe sat in judgment the whole day long, for then when was his Torah learned; rather it comes to teach that any judge who judges a true judgment, even for a single hour, the passuk counts it for him as though he became a partner with HaKadosh Baruch Hu in maaseh bereishit. And on the verse in Vayikra, “and you shall afflict your souls on the ninth of the month,” he taught the source for tosefet Shabbat: one begins the fast while it is still day, from which we learn that one adds from the chol onto the kodesh — at its entrance and at its departure, and not for Yom Kippur alone but for Shabbatot and Yamim Tovim as well.