Rabbi Avraham ben Yitzchak of Narbonne—Sefer ha-Eshkol רבי אברהם בן יצחק מנרבונה — ספר האשכול

Three Provençal sages are called by the one acronym Raavad, and they are easy to confuse. This is the eldest: Rabbi Avraham ben Yitzchak, av beit din of Narbonne, whose signature stands under the ordinances of all Languedoc.

His book is the Sefer ha-Eshkol, the Cluster. It is built as a code: law by subject, resting on the Rif and on the Sefer ha-Ittim of Rabbi Yehuda of Barcelona, but with the Provençal custom where that custom is its own. From it one sees how this land differed: Spain followed the Rif, Ashkenaz followed Rashi and the Tosafot, and Provence held both—which is why Provençal books so often turn out to be the bridge between two worlds.

His daughter married Rabbi Avraham ben David of Posquières—the Raavad whose objections are printed beneath the Mishneh Torah. So the two chief heads of Provence became one family.