opinions This fanciful narrative was largely accepted by his contemporaries as true. Its origins are to be found in the aggadic literature, of which Eldad must have had a very extensive knowledge. The inhabitants of Kairouan were troubled by the differences between his halakhot and those of the Talmud, and by some of his strange Hebrew words. Eldad pretended to speak only Hebrew, however, many of the words in his letters are derived from Arabic, suggesting that he may have understood other languages as well. The gaon Ẓemaḥ ben Hayyim of Sura, whose opinion they had asked, soothed them by saying that there was nothing astonishing in the four tribes disagreeing with the Talmud on some halakic points. Moreover, Eldad was known to the Gaon through Isaac ben Mar and R. Simḥah, with whom the Danite associated while he was in Babylonia. Hisdai ibn Shaprut cites Eldad in his letter to the king of the Khazars, and Eldad's halakhot were used by both Rabbinites and Karaites as weapons in defense of their respective creeds. Talmudic authorities like Rashi, Abraham ben David, and Abraham ben Maimon quote Eldad as an unquestioned authority; and lexicographers and grammarians interpret some Hebrew words according to the meaning given them in Eldad's phraseology. However, many writers of the Middle Ages expressed doubts as to the genuineness of Eldad's narrative and his halakhot, most explicitly Abraham ibn Ezra (Commentary to Exodus ii. 22) and Meir of Rothenburg (Responsa, no. 193). 19th century opinions Nineteenth-century critics were divided in their opinions concerning Eldad. Simhah Pinsker, Heinrich Grätz, and Adolf Neubauer saw in him a Karaite missionary endeavouring to discredit the Talmud through his statement that the four tribes did not know the names of the Tannaim and Amoraim, and that their halakhot were different from those of the Talmud. This opinion was refuted by Moses Schorr and Adolf Jellinek, who observed that Eldad's halakhot contain rules of shechita not accepted by the Karaites. P. F. Frankl regarded Eldad as a mere charlatan whose sayings and doings are not worth attention. Jacob Reifmann denied outright the existence of Eldad, and considered the letters of the community of Kairwan and of Ẓemaḥ ben Ḥayyim of Sura to be forgeries. Metz was the first to analyze the contents of Eldad's book in the light of the reports of other travellers. Abraham Epstein followed Metz's method, and came to the conclusion