In Fez, Maimon and David built a successful jewelry business while Maimonides continued to devote himself to His studies, particularly of medicine. Once again, the family lived quietly for a time, and once again their peaceful life was shattered—this time by Maimonides himself. In about 1162, he published his first significant work, translated as Letter Concerning Apostasy. Apostasy means rejection of a religious faith, and in this case referred to the Jews' rejection of Islam in favor of holding on to their traditions.
Maimonides's work gave comfort to many, and made him an instant celebrity within the Jewish community, but in light of his sudden prominence, the family judged it wise to leave Morocco. In 1165, they moved to Palestine, but after five months they relocated to Alexandria, Egypt. There tragedy struck a double blow: first Maimon died, then David drowned. Maimonides was devastated, particularly by the death of his younger brother, and he later recalled that for a whole year his grief prevented him from moving on with his life.
But he had to move on, especially because now, at the age of thirty, Maimonides had the responsibility of supporting David's widow and children. Settling in Cairo, he began to make a living as a physician, and he continued his studies. At some point he had married, but his first wife died. Soon afterward, he remarried and had two children, a girl and a boy. The son, Abraham, would later follow in Maimonides's footsteps as a leader in Cairo's Jewish community—as would ten more generations of his family.