Rabbi Moshe ben Yosef di Trani, known as the Mabit, was born in 1500 in Salonica, three years after his father, Rabbi Yosef di Trani, arrived there; the family were scholars among the Spanish exiles and traced their descent to Rabbi Yeshayah di Trani.

As a boy he studied in Adrianople, in the yeshiva of Rabbi Yosef Fasi and under his uncle Rabbi Aharon di Trani. At eighteen, in 5278, he went up to the Land of Israel and settled in Safed, where he became the foremost disciple of Rabbi Yaakov Beirav. At twenty-five he was appointed to his teacher's rabbinical court, and received semichah from him together with Rabbi Yosef Karo.

He sat on the Safed rabbinical court for fifty-four years, teaching Torah and answering questions sent to him from across the Jewish world. A colleague of Rabbi Yosef Karo, with whom he often debated halachah, he headed the court for five years after Karo's death. He corresponded with the Radbaz, Rabbi Betzalel Ashkenazi and Rabbi Moshe Alshich, and in 1556 supported the boycott of the port of Ancona proclaimed after conversos who had returned to Judaism were burned there.

Works: Kiryat Sefer (Venice, 1551), which determines for each law in the Rambam's Mishneh Torah whether it is of Torah or rabbinic origin; Beit Elokim (Venice, 1576), in three sections on prayer, repentance and the foundations of faith, with the first printed commentary on Perek Shirah; Iggeret Derech Hashem (Venice, 1553); a commentary on a treatise of Rav Saadia Gaon; and his responsa, She'elot uTeshuvot HaMabit, some eight hundred responsa published by his sons about fifty years after his death.

He passed away in Nissan 5340 (1580), on the last day of Pesach according to one source. He left two sons: Rabbi Shlomo, a rabbi in Egypt, and Rabbi Yosef di Trani, the Maharit, one of the great halachic authorities of his generation. He is buried in the Old Jewish Cemetery of Safed.