Jacob ben Asher, in Hebrew Ya'akov ben Asher, (1270-ca 1340 (Toleo, Spain) was an influential Medieval rabbinic authority. He is often referred to as the Baal ha-Turim ("Master of the Turim (Pillars)"), after his main work in halakha (Jewish law), the Arba'ah Turim. He was the third son of the Rabbi Asher ben Jehiel (known as the "Rosh"), a German-born Rabbi who moved to Spain. Besides his father, who was his principal teacher, Jacob quotes very often in the Turim his elder brother Jehiel; once his brother Judah (see Tur Orach Chaim, § 417), and once his uncle R. Chaim(ib. § 49). According to many, Jacob moved to Spain with his father and was not born there.