Moses ben Maimon (1135-1204)

Although  he did use Hebrew in some of his works, most of them were actually written in Arabic   He is famed for his  "radical" philosophical work on the unity of reason and faith, Guide for the Perplexed, which was heavily criticized in the Jewish world (especially by Franco-German rabbis). Maimonides'  greatest work was his Mishna Torah, a guide in fourteen sections to Jewish traditions and  practices, which was based on the entire  Talmud (both the Babylonian and Jerusalem versions). It is written in  the purest Hebrew and was later called the Rambam (his initials) in Maimonides' honor. He was a prodigious correspondent, answering questions from all over the world. His letter to Yemen,  Igeret Teiman, written in Arabic, comforted the community  during difficult times. In the letter he discussed the relations with Christianity and Islam  and encouraged the Jews, from a historical perspective, to be strong.