Yaaqov ben Yitsḥaq Tsahalon (also: Jacob ben Isaac Ẓahalon; 1630-1693), born in Rome, was an Italian rabbi and physician. Acquiring early a high reputation both as physician and Talmudist, he was called to the rabbinate of Ferrara and held this position until his death. He was the author of the Otsar he-Ḥayyim, a medical work in thirteen parts, the last of which remained unpublished for lack of funds (Venice, 1683), and of the Margaliyyot Ṭovot, an abridgment of the Ḥovot ha-Levavot of Baḥya b. Joseph ibn Paḳuda, divided into thirty chapters corresponding to the number of days of the month, each chapter being followed by prayers for various occasions (ib. 1665). In his preface Tsahalon enumerates the following works which he left in manuscript: "Morashah Ḳehillat Ya'aḳob," on Maimonides; "Yeshu'ot Ya'aḳob," a commentary on Isaiah; "Titten Emet le-ya'aḳob," homilies on the Pentateuch; "Ḳol Ya'aḳob," an index to the Yalḳuṭ, called also "Or ha-Darshanim" ("Oẓrot Ḥayyim," No. 30); "Ẓahalah u-Rinnah," on the Song of Solomon; "Ḳohelet Ya'aḳob," on Ecclesiastes; "Derushim 'al-Daniel," on Daniel; "Milḥemet Ya'aḳob," subject unknown; "Oẓar ha-Shamayim," on theology and philosophy; and "Shubu Elai," on the Shema'' and the benedictions which accompany it. Jacob was much consulted on halakic questions by his contemporaries. His decisions and responsa are found in the "Teshubot ha-Remez" of Moses Zacuto (§ 36), in the "Paḥad Yiẓḥaṭ" (s.v. ) of Isaac Lampronti, and in the "'Afar Ya'aḳob." of Nathanael Segre; the last-named declares that Jacob was one of the three most learned men of his generation.