He then settled in Zaragoza, where he wrote Kitab al-Mustalhaq, which expanded on the research of Judah ben David Hayyuj and led to a series of controversial exchanges with Samuel ibn Naghrillah that remained unresolved during their lifetimes.
[7] He is also called by the Arabic ism Marwān (Ibn Ezra cites him as "Marinos")[a] and by the kunya Abū al-Walīd, which was often given to men named Jonah.
[1][11] His education included the languages of Arabic, Hebrew, and Aramaic, tafsir or exegesis of the Bible and the Quran, as well as rabbinic literature.
[11] Córdoba was besieged and sacked by Berber rebels, who committed atrocities on its citizens, including the Jews.
[16] Today, the only extant manuscript of this work is preserved in the Süleymaniye Library in Istanbul, Turkey (MS Aya Sofia 3603, fols.
[19] In the Kitāb al-mustalḥaq, ibn Janah praised Hayyuj's works and acknowledged them as the source for most of his knowledge of Hebrew grammar.
[11] They were offended when ibn Janah, a relatively junior scholar at the time, criticized their master and found his works incomplete.
Most chapters are subdivided into three parts, the first on medicinal drugs (mainly plant-based), the second on weights and measures and the third on difficult terms.
[22] Towards the end of his life, ibn Janah wrote what is considered his magnum opus,[13] the Kitab al-Tanqīḥ ("Book of Minute Research", known in Hebrew translation as the Sefer haDiqduq).
[27] The twelfth-century biblical commentator Abraham ibn Ezra strongly opposed it and called it "madness" close to heresy.
[28] Ibn Janah defended his method by pointing to precedents in the Talmud as well as previous works by Jewish writers in Lower Mesopotamia and North Africa, which all used examples from other languages to define Hebrew words.
[29] Ibn Janah died in approximately 1055,[13] his works quickly became popular among Hebrew scholars in Spain.
[29] However, in the late twelfth century, Spanish-Jewish scholars in Italy and the sages of Occitania in southern France spread ibn Janah's work there and to the rest of Europe.
[25] Hebrew scholars and exegetes subsequently cited him in the Iberian peninsula, the Middle East and southern France.
The Encyclopedia of Jews in the Islamic World (EJIW) describes him as "one of the best-known, most influential, closely followed, and highly praised scholars" of Hebrew.
[4] Writer David Tene "rhapsodizes" on the Kitāb al-Lunaʿ, calling it "the first complete description of Biblical Hebrew, and no similar work - comparable in scope, depth and precision - was written until modern times...[it was] the high point of linguistic thought in all [medieval grammatical] history".
[25] The Jewish Encyclopedia, however, notes "serious gaps" in the Kitāb al-Tanqīh, because it does not discuss vowels and accents, and because it omits to explain Hayyuj's works on which it is based on.
[33] The Encyclopædia Britannica calls him "perhaps the most important medieval Hebrew grammarian and lexicographer" and says that his works "clarif[ied] the meaning of many words" and contained the "origin of various corrections by modern textual critics".