Abraham Hirsch ben Jacob Eisenstadt of Byelostok

Abraham Hirsch ben Jacob Eisenstadt of Byelostok (1812–1868) (Hebrew: אברהם צבי הירש בן יעקב אייזנשטאט) served as rabbi in Utyan (Utena), government of Kovno. He began at an early age to write his important work, Pithe Teshubah (פיתחי תשובה), which is the most popular and useful index to the responsa and decisions of later authorities on the subjects treated in the Shulḥan 'Aruk. Eisenstadt's great merit consists in having collected all the material given in the works of his predecessors, and in having added to it an almost complete collection of references to responsa of all the later eminent rabbis. Of lesser value are the novellæ which Eisenstadt added to the Pitḥe Teshubah under the title Naḥalat Ẓebi. The part of the Pitḥe Teshubah on Yoreh De'ah was published at Vilna in 1836 (republished Jitomir, 1840, and Lemberg, 1858); that on Eben ha-'Ezer, in 1862; and, after the author's death, that on Ḥoshen Mishpaṭ, in Lemberg, 1876 (republished in Vilna, 1896).

Eisenstadt is also the author of a commentary on the Seder Giṭṭin wa-Ḥaliẓah, by Michael ben Joseph of Cracow, Vilna, 1863, 2d ed. 1896. Abraham Hirsch died in Königsberg in 1868.