ר׳ אליעזר בן נתן

ר׳ אליעזר בן נתן of Mainz, known by the acronym ראב״ן, was a formative twelfth-century Ashkenazic halakhist, Tosafist, liturgical poet and chronicler. Born around 1090 in Mainz, shortly before the First Crusade devastated the Rhineland communities, he studied with early disciples of ר׳ שלמה יצחקי, especially ר׳ יצחק בן אשר הלוי. He married a daughter of ר׳ אליקים בן יוסף ממגנצא and became a central authority of the ShUM communities. His compendium אבן העזר—commonly called ספר ראב״ן—combines legal decisions, responsa, Talmudic discussion, customs and liturgy, and is among the earliest broad Ashkenazic halakhic works. He also composed piyyutim and a Hebrew account of the 1096 persecutions, an indispensable source for Crusade-era Jewish history. His responsa reflect contacts with France and Slavic lands, though many proposed journeys cannot be dated securely. Around 1160 he participated in the rabbinic assembly at Troyes alongside ר׳ שמואל בן מאיר and ר׳ יעקב בן מאיר. Through his daughters he became ancestor to major scholarly families; his grandson was ר׳ אליעזר בן יואל הלוי, the ראבי״ה. He died around 1170.