Abraham ha-Yakini was one of the chief agitators in the Sabbatean movement, the son of Pethahiah of Constantinople. He was born—according to a not entirely reliable source, מאורעות צבי (Lemberg, 1871, p. 3)—on September 8, 1611. He studied under Joseph di Trani of Constantinople (died 1644), and under Mordecai, a German kabalist.