Isaac ben Sheshet

Isaac ben Sheshet Perfet or Barfat (Hebrew: יצחק בן ששת; 1326–1408) was a Spanish Talmudic authority, also known by his acronym, Rivash (ריב"ש‎). He was born in Valencia and settled early in life in Barcelona, where he studied at the school of Nissim of Gerona.