Hasdai sent rich presents to the yeshiva of Sura and that of Pumbedita in Babylonia, and corresponded with Dosa, the son of Saadia Gaon. He was also instrumental in transferring the center of Jewish theological studies from Babylonia to Spain, by appointing Moses ben Hanoch, who had been stranded at Córdoba, director of a school, and thereby detaching Judaism from its dependence on the East, to the great joy of the caliph, as Abraham ibn Daud says ("Sefer ha-Kabbalah" p. 68). Ibn Abi 'Usaybi`a writes of him: "Hasdai b. Isaac was among the foremost Jewish scholars versed in their law. He opened to his coreligionists in Andalusia the gates of knowledge of the religious law, of chronology, etc. Before his time they had to apply to the Jews of Baghdad on legal questions, and on matters referring to the calendar and the dates of the festivals" (ed. Müller, ii. 50).