Beginning in about 1057, the city of Kairouan was attacked and ransacked repeatedly, and eventually the entire Jewish community was forced out of the city. For the last two to five years of his life, R. Nissim lived in Mahdia (on the Tunisian coast).2
Occupation – R. Nissim is noted in multiple letters as a ריש בי מדרש, the head of a rabbinic study hall in Kairouan.3
Family – His father, R. Yaakov b. Nissim, was an important rabbinic figure in Kairouan; R. Yaakov was responsible for the strong connection between Kairouan and the Yeshiva of R. Hai Gaon in Baghdad.4 Accroding to R. Avraham ibn Daud, the daughter of R. Nissim was married to Yehosef, the son of R. Shemuel HaNagid.
Teachers – R. Hai Gaon,5 R. Hushiel b. Elhanan (the father of R. Hananel).6
Contemporaries – Rabbeinu Chananel, R. Shmuel ha-Nagid, Shelomo ibn Gabirol
Time period – R. Avraham ibn Daud and R. Menachem Meiri refer to R. Nissim as one of three rabbis who make up the first generation of Rabbanim, the successors to the Geonim.7
World outlook – In introductions to his works, R. Nissim expresses his desire to use his books in order to lift people's spirits8 and ease the Torah study of his students.9
Works
Biblical commentaries – Although there is no record of any Torah commentary by R. Nissim, because many of his responsa deal with questions of biblical texts, he is cited by many classical Torah commentaries, such as R. David Kimhi10 and Ramban.11
Rabbinics –
Talmudic novellae – Sefer ha-Mafteach, a work cross-referencing the Talmud and documenting citations of other rabbinic statements in the Talmud was composed on several tractates (although the only complete sections that have survived are on Berakhot, Shabbat, and Eruvin). R. Nissim also composed a separate commentary on Eruvin, and possibly other tractates or chapters.12
Halakhic codes – An incomplete manuscript of R. Nissim's work (in Arabic) on the Laws of the Four Species has been published. External evidence indicates that R. Nissim wrote halakhic works on the laws of Purim, Shomrim, and perhaps other topics.13
Responsa – At least 200 responsa of R. Nissim were collected (in his lifetime) into a compendium with the title of Megillat Setarim.14
Rabbinic Legends – With the goal of comforting his son-in-law after the loss of a child, R. Nissim composed a book called Hibur Yafeh me-haYeshuah comprising of rabbinic tales from Talmud, Midrash, and other sources demonstrating God's providence in ensuring that the righteous are rewarded.15
Writings
Characteristic Features
Comprehensiveness – Throughout his writings, but most prominently in his Sefer ha-Mafte'ah, R. Nissim presents a topic by referencing nearly all of the relevant rabbinic material from a wide variety of sources (from Mishnah, Tosefta, Talmud, and Midrash).16
Language – R. Nissim appears to have mostly written in Arabic, with the possible exception of his commentary on Eruvin and some letters of responsa.17
Parshanut – In one passage, R. Nissim expresses surprise that R. Shmuel b. Hofni Gaon would understand a biblical verse differently than Targum Onkelos, indicating that R. Nissim himself understood this translation to preclude alternative readings of the verse.18
Methods
Bavli and Yerushalmi – Whenever possible, R. Nissim incorporates teachings of the Talmud Yerushalmi in explaining the Talmud Bavli.19
In cases of contradictions between the two talmuds, R. Nissim is recorded in one instance as stating explicitly that the Talmud Bavli is more authoritative.20
Themes
Reason – R. Nissim frequently writes how he attempts to explain rabbinic teachings "in accordance with reason," especially to defend their words against those who question their authority or wisdom21
Philosophy– In one letter, R. Nissim demonstrates how the rabbis recognized a philosophical principle on the nature of knowledge.22
Inspiration – the book Hibur Yafeh miYeshuah was written with express purpose of providing solace to its readers, and in other instances R. Nissim likewise demonstrates an interest in explaining rabbinic teachings in ways that would make them more relevant and inspiring.23