||R. Eliezer b. Nathan of Mainz (known as RaBaN=Rabbi Eliezer Ben Nathan; c. 1090–c. 1170), one of “the elders of Mainz” and a leading rabbinic authority in Germany in the 12th century. R. Eliezer was apparently born in Germany and in his youth seems to have studied with rabbis of Mainz. Later he lived for a time in the Slavic countries, and possibly in Russia. He then returned to Mainz, where he married the daughter of R. Eliakim b. Joseph, of whose rabbinical court he was a member. Among his four sons-in-law were R. Samuel b. Natronai and R. Joel b. Isaac ha-Levi. He was also related to R. Ephraim b. Jacob of Bonn and R. Jacob b. Isaac ha-Levi. It is doubtful whether R. Asher b. Jehiel was a descendant of his. When the latter refers to zekeni ha-Rabban, the quotations are mainly from the Ravyah of R. Eliezer b. Joel ha-Levi. His contemporaries in France and Germany recognized his authority, and they addressed him in terms of great respect. In 1150, together with R. Jacob b. Meir Tam and R. Samuel b. Meir, he drew up the famous Takkanot Troyes (the Troyes Ordinances).
His great work (Sefer ha-Raban) which he called Even ha-Ezer (“Stone of Help”) is the first complete book that has survived emanating from German Jewry. It contains responsa and various extracts and halakhic rulings following the order of the talmudic tractates. The book appears to have come down exactly as R. Eliezer wrote it (but cf. Sefer ha-Raban, p. 106a), although there is no logical continuity from one section to the next and there are a number of omissions. The section numbers are by R. Eliezer himself, who used them for internal reference purposes, but in the printed editions they are deleted from b385 onward. The book contains expositions of talmudic topics and commentaries on customs, liturgical passages, including the kaddish, as well as interpretations of various Midrashim and of chapter 31 of Proverbs, together with correspondence with over 20 rabbinical authorities of the day.
The book contributes much to knowledge of the way of life of the Jews of France and Germany in the 12th century, and is a mine of information on the state of scholarship and religious practice in France, Germany, and Babylonia. Special mention should be made of R. Eliezer's considerable use of the talmudic commentary of R. Hananel b. Hushi'el (“Rabbenu Hananel”; often without mention of the source) only about 50 years after it appeared. Most likely R. Hananel's commentaries came to him from the Arukh of R. Nathan b. Jehiel of Rome whom he also quotes. The citations from R. Hananel are rendered more accurately by R. Eliezer than by other early authorities. Eliezer is also the first to cite the anonymous Sefer ha-Mikzo'ot.
There is some confusion with regard to the book Zafnat Pa'ne'ah (“Revealer of Secrets”), which the early authorities cite frequently, and which they attribute to R. Eliezer. The fact that many of the quotations appear in the Even ha-Ezer indicates that it may have been known by two names. Another opinion is that the reference is to a shorter edition of the book, while still another view is that there was an entirely different book, from which the copyists added to the Sefer ha-Raban that has been preserved. Another book ascribed to R. Eliezer, Even ha-Roshah, which is in manuscript, is merely a compilation from “Hilkhot Dinin” in the Sefer ha-Raban (pp. 92ff.), corresponding in all respects with a similar compilation printed in the Kol Bo. Sefer ha-Raban was first published in Prague (1610) and subsequently (only as far as tractate Niddah) by S. Albeck, who added a long introduction in Warsaw (1905). Part of it was published in Jerusalem (1915) by R. Leib Raskes, and the entire work was published by R. Solomon S. Ehrenreich (Simleul-Silvaniei, 1927), who wrote an extensive commentary to it.
R. Eliezer was the first commentator on piyyut in Germany. Part of his commentaries are preserved in manuscript, of which only fragments have been printed, often interspersed with selections from the commentaries of other early authorities in mahzorim published in Ostrog (1810, 1817 et al.) and Slawita (Mahzor Korban Aharon, 1826, et al.). An old manuscript, given to the editors by R. Epphraim Zalman Margaliot, served as the basis for this printing. Another incomplete manuscript was in the possession of Solomon Zalman Halberstam (Kehillat Shelomo, Vienna, 1890). R. Eliezer's commentary encompassed the entire mahzor, the complete siddur for Sabbaths and weekdays, the Haggadah, and Pirkei Avot (“Ethics of the Fathers”). He has mistakenly been credited with the authorship of the anonymous Ma'amar Haskel (Cremona, 1557), a commentary on his own piyyut El Elohim ha-Shem Dibber. The commentary was actually written more than 100 years after his time. It is also doubtful whether he is the author of the commentary on the kinah of R. Kallir, Eikhah Yashevah Havazzelet ha-Sharon, published by J. H. Schorr. Of R. Eliezer's piyyutim, some have been printed and others are extant only in manuscript. The horrors of the First Crusade form the theme of some of his piyyutim. He also devoted a special booklet to this subject, Kuntres Gezerot “Tatnu” (“Booklet on the Massacres of 1096,” publ. Leipzig, 1854). His commentary on Avot (also included in the above-mentioned manuscript owned by Margaliot), was in the possession of Jehiel Michael Moravchik, who made use of it “from the manuscript of the RaBaN written in 1145” in his own commentary on Avot (Minhah Hadashah, Cracow, 1576). A didactic poem by R. Eliezer on the laws of shehitah was published in Sefer ha-Yovel le-Rav Shimon Skop (Vilna, 1936). In Sefer ha-Roke'ah (§319) he is credited with having written a book on customs.
||ספר ראבן ... שעד עתה לא נדפס בדפוס ... מאיזה סיבות וגזירות: היה טמון וגנוז וכמוס ... כחמש מאות שנים ... ושאלנו ולא שמענו משום אדם שראה או ששמע ... ממהות זה הספר ... הנקרא אב"ן העזר. שחיבר הרב רבינו אליעזר בר נתן הנקרא ראב"ן בפי
כל הפוסקים ... דברים חדושים ... בפסקים דינים ומשפטים ישרים וגם פיר' עמקי הלכות ושיטות בכל שיטות התלמוד באשר שהם סדורים ... ומנהגי מנהג וותיקין מקדמונים ... ע"פ הגמרא ושיטת התלמוד בששה סדרים ...
מעבר לשער: [הסכמת] ר' מרדכי נקרא יפה, ר' יוסף ב"ר אברהם שפירא , ר' שמואל אליעזר ב"ר יודא הלוי [אידלש], ר' דוד ב"ר יצחק , ר' אברהם לבית לוי ב"ר יודא ס"ל, ר' אליהו ב"ר מרדכי, ר' שלמה אפרים ב"ר אהרן איש לונטשיץ, ר' יצחק ב"ר שמשון
כ"ץ, ר' משה ב"ר דוד הלוי, ר' מרדכי ב"ר אליה ליפשיץ, פוזנא, יג מנחם [אב] שס"ט.