Jacob ben Asher

Jacob ben Asher (c. 1269–1340), called Ba'al ha-Turim, was a German-born rabbinic authority active in Castile. Third son of the rabbi Asher ben Jehiel, the Rosh, he was born at Cologne and in 1303 moved to Toledo after his father fled persecution in Germany. Schooled by his father, he lived in poverty.

His legal code Arba'ah Turim, the Four Columns, arranged Jewish law in four parts and gave him his byname. He died about 1340, at Toledo, or on a journey at Chios.