Hager was born in
Kolomyia (modern-day Ukraine) to Rabbi
Yaakov Koppel Hager and his wife Chaya. He studied under Rabbi
Moshe Leib of Sasov, Rabbi , Rabbi
Meshullam Feivush Heller, and Rabbi . From an early age, he devoted most of his life to Torah study and only engaged in commerce enough to earn a living for basic necessities. He accepted the position of rabbinate in
Kosov and became the mentor to thousands of Hasidim. He, along with his wife Rebbetzin Shaina Rachel, was the first member of the Kosov Hasidic of the Hager family, of which came the subgroups of
Vizhnitz Hasidism, , and others. Becoming popular among Hasidim, Rabbi
Simcha Bunim of Peshischa said that his feet burned to want to meet the rebbe of Kosov. The
Seer of Lublin referred to him as a "king". After the death of his wife, Rabbi Moshe Leib of Sasov sent two children, a boy and a girl, to Hager, his former student, to take care of their upbringing and education. Moshe died about three months later. Among Hager's students were: • Rabbi of
Bucecea • Rabbi • Rabbi He died on 29 October 1825. == Family ==