He received a medical training in his native country as a Marrano, but fled about 1619 to Safed and devoted himself to the Talmud and the casuists ("poseḳim") until 1625; then he went to Damascus, where for eighteen years he studied kabbalah from the Zohar and the writings of Isaac Luria and Hayyim Vital.
He finally settled at Jerusalem and opened a yeshivah for the study of the Zohar and other kabbalistic works, David Conforte being for some time one of his pupils.
[1] Jacob Ẓemaḥ was one of the greatest kabbalists of his period and was a prolific author, his works including treatises of his own as well as compilations of the writings of Ḥayyim Vital.
His second published work is the Nagid u-Meẓawweh (Amsterdam, 1712), on the mystical meaning of the prayers, this being an abridgment of a compendium which Ẓemaḥ composed on the basis of a more comprehensive treatise.
Among his unpublished works, special mention may be made of the Ronnu le-Ya'aḳob, in which he calls himself "the proselyte" ("ger ẓedeḳ").