[3] Tanhum authored two main works: Kitāb al-Bayān ("Book of Elucidation") - A Commentary on the Prophets and Hagiographa, and Al-murshid al-kāfī ("The Sufficient Guide") - A comprehensive and detailed lexicon arranged in alphabetical order in which he defines difficult words found in the Mishnah and in the writings of Maimonides, namely, in his Mishne Torah.
An old copy of his Al-murshid al-kāfī had been preserved in Yemen, and, because of its unique style, was thought by Avraham Al-Naddaf to have been penned in the Yemenite dialect of Arabic.
Today, a handwritten manuscript of his Hebrew lexicon, al-Murshid al-kāfī, is preserved at the Bodleian Library in Oxford University,[5] as well as other Mss.
The first part of the lexicon (up to kāf, the eleventh letter of the Hebrew alphabet) was published in 1961, translated by Rabbi Barukh Avraham Toledano.
[6] In 2006, the entire dictionary was republished, based on the 2nd edition of the Murshid and translated into Hebrew by Hadassah Shai of the National Academy of Sciences in Israel.
Tanhum's works on Hebrew grammar are mainly founded upon the writings of the Spanish grammarian, Jonah ibn Janah.