 There are not many sources on the life of Abner. The majority of the sources are autobiographical passages in his works (especially Mostrador de Justicia). Abner was born around 1260, probably in the Jewish community of Burgos, one of the major communities in Castile. While still Jewish, Abner worked as a book trader, a rabbi, and he may have been a physician as well. During this time he was the head of a yeshiva (Jewish academy) in Burgos, but we do not know if this yeshiva was a public institution or just a private group of students that met in his home. We know from a former pupil, Rabbi Isaac Pulgar, and from the sources that he utilizes in his works, that during the Jewish period of his life, Abner was a philosopher, being a part of the Maimonidean-Averroist trend of Jewish philosophy at the time.