Or Zarua

Rabbi Yitzchak the son of Moshe was born in Bohemia in 1180. He attained his fame in Vienna, where he lived until his death in 1250. His work, the Or Zarua, is a halachic guide arranged according to the Talmudic tractates, and was very popular among Ashkenazic Jewry. He was a member of the Chassidei Ashkenaz and studied under many people, including the Ra'avyah and Rabbi Elazar Rokeach. He was among the teachers of Rabbi Meir of Rothenburg.