Rav / Abba Arika

Abba bar Aivu, called Abba Arikha ("the tall") and known simply as Rav, "the master," was a Babylonian Jew who went to the Land of Israel with his uncle Rabbi Hiyya and studied under Rabbi Yehudah HaNasi, in the last stage of the Mishnah's editing. According to the Epistle of Rav Sherira Gaon, he returned to Babylonia around 219 and later founded the academy at Sura on the Euphrates, where he taught until his death in 247. His authority was so great that the Talmud says "Rav is a Tanna and may dispute" the earlier sages (Eruvin 50b).

Rav and his colleague Shmuel of Nehardea opened the age of the Babylonian Amoraim. Their many debates fill the Talmud, and the rule is that the law follows Rav in ritual matters and Shmuel in civil law (Bekhorot 49b). Tradition credits Rav with composing the Rosh Hashanah Musaf prayers, including Aleinu, and his personal prayer recorded in Berakhot 16b became the blessing for the new month recited in synagogues on the Shabbat before Rosh Chodesh.