Yahrtzeit of Rabbi David ibn Abi Zimra (1480-1573), known by the acronym of his name, Radbaz. He served as the Chief Rabbi of Egypt and later moved to Israel. He taught Jewish mysticism to the Arizal (Isaac Luria) who went on to become the founder of modern Kabbalah. The Radbaz issued many important decisions in Jewish law, including the assertion that the Ethiopian community was certainly Jewish -- a decision that gained practical application in the 20th century with the airlift of Ethiopian Jews to Israel.