Abraham ben Isaac
Abraham ben Isaac of Narbonne, France lived during the middle of the 12th century. He was the leading legalist and spiritual leader of Provence. Abraham studied under Meshullam b. Jacob of Lunel. He also spent some time in Barcelona, where he became very familiar with R. Judah b. Barzillai's work, Sefer Ha-Ittim.
Upon his return to Provence, ben Isaac became the head of Narbonne's Jewish court. Benjamin MiTudelo described him as head of his yeshiva. Among his students was Abraham b. David of Posquieres.
He is best- known for his book Sefer HaEshkol. In it, ben Isaac excerpted and summarized the traditions written in Judah b. Barzilai's voluminous Sefer Ha-Ittim. This introduced Spanish Jewish customs to southern France. At the same time, ben Isaac included and incorporated the different rituals and customs of Narbonne. He also commented on regulations and rituals practiced by North France's Jewry. He included them as law as he thought best.
Sefer HaEshkol encouraged French Jewry to take more seriously the scholarship of Spanish Jewry and to see the similarities in their customs and rituals. Ben Abraham created one of the first cultural and religious bridges between Sephardic and Ashkenazic customs.
Sources: Gates of Jewish Heritage