Al-Samaw'al · Public domain

Al-Samawal al-Maghribi was a leading mathematician, astronomer, and physician in twelfth-century Islamic Spain and North Africa, the son of a Moroccan rabbi, who made early contributions to algebra including work on binomial coefficients and algebraic notation that later mathematicians built on. He converted from Judaism to Islam in 1163, after keeping the decision private for years for fear of hurting his father, before finally acting on what he described as a dream instructing him to do so.