Isaac ben Sheshet

Isaac ben Sheshet Perfet (1326 – 1408) (Hebrew: יצחק בן ששת) was a Spanish Talmudic authority, also known by his acronym, Rivash (ריב"ש). He was born at Valencia and settled early in life at Barcelona, where he studied under Perez ha-Kohen, under Hasdai Crescas, and especially under R. Nissim ben Reuben (RaN), for whom he professed throughout his life the greatest veneration.