יהודה בן ברזילי הברצלוני

Rav Yehudah ben Barzillai of Barcelona (late 11th to early 12th century), known as HaNasi, was among the great chachamim of Sefarad and one of the foremost codifiers of halachah of his age. Little is known of his life. He was a contemporary of Rav Avraham bar Chiyya HaNasi, with whom he had a well-known disagreement: bar Chiyya, who held by the stars, wished to postpone a wedding for unfavorable omens, while the rishon ruled that to heed such omens is forbidden by the Torah. Rav Avraham ben Yitzchak, the Rabad, knew him and consulted him in difficult questions.

His halachic writings covered the whole of the law, ritual and civil, and were cited as authoritative by the rishonim, though most of them have been lost. His best-known work is Sefer haIttim, on the halachot bound to their times; the surviving fragments deal with the laws of Shabbat and eruvin. His Sefer haDinim on civil law survives in part as Sefer haShetarot, on the forms of contracts according to halachah, and he also wrote a lengthy commentary on Sefer Yetzirah that draws on the works of the Geonim, some otherwise unknown. The Chida praised him in Shem HaGedolim as the author of a great and weighty work on the whole of the Talmud.