RAV (lit., "rabbi"), epithet of Abbaʾ bar Ayyvu (c. 155–c. 247), a first-generation Babylonian amora. Rav helped lay the foundations for rabbinic Judaism in Babylonia. He studied in Palestine with his uncle Ḥiyyaʾ and with Yehuda ha-Nasiʾ, from whom he reportedly received authorization to render decisions in many areas. These contacts gave him a rich reservoir of teachings, self-reliance, and the freedom to go beyond tannaitic traditions.

Later Talmudic circles considered his resettlement in Babylonia, conventionally dated to 217, a turning point in Jewish history, one presaged by natural omens (B. T., Shab. 108a). First dwelling in Nehardea, a city on the Euphrates River, he assisted other rabbis and served as a market administrator (J.T., B.B. 5.11[5]; 15a–b). He later moved to Sura, a town hitherto said to lack a rabbinical presence. There he gathered a circle of students but probably did not head an academy, as was...