Rabbi Yeshaya HaLevi Horowitz, the Shelah HaKadosh, was born in Prague around 1555-1558, the son of Rabbi Avraham HaLevi Horowitz, a student of the Rema and author of Chesed Avraham, of a renowned rabbinic family. He studied in Lublin under the Maharam of Lublin and Rabbi Shlomo Leibush, and under Rabbi Yehoshua Falk. He married Chaya, daughter of Avraham Moul of Vienna, and was a wealthy patron who supported Torah study, especially in Jerusalem. In 1590 he took part in the Council of Four Lands in Lublin.

He served as av beit din of many communities in Poland and Germany, including Frankfurt and Prague, before going up to the Land of Israel in 1621. His major work, the Shnei Luchot HaBrit (Shelah), combines halacha, ethics and Kabbalah into a complete guide to Jewish life. It had an immense influence on the piety of European communities and on the Chassidic movement. He also composed the Shaar HaShamayim siddur and the famous prayer of parents for their children, recited on the eve of Rosh Chodesh Sivan.

In Jerusalem, where he led the Ashkenazi community, he was imprisoned by the Ottoman governor and released for a ransom. He then settled in Safed and later Tiberias, where he rests near the Rambam. The date of death fixed by tradition is 11 Nisan 5390 (1630), though some scholars place it earlier.