Excommunication and apostasy: re-drawing Jewish communal boundaries in Fāṭimid and Ayyūbid Egypt

When Ben al-Qābisī, a Jewish merchant, reached Alexandria, sometime in the early years of the twelfth century, he had already been excommunicated for quite some time on the other side of the Mediterranean, in al-Andalus. He was excommunicated in Granada, as well as in Lucena, the Jewish centre of study in Islamic Iberia, in the presence of “the Rabbi, the righteous, may his memory be a blessing.” The excommunication was likewise reiterated in Cordoba and Seville in the presence of Jewish dignitaries. This much was known in Alexandria when Ben al-Qābisī arrived at the port, and some of his fierce rivals were there, promoting a reiteration of the excommunication in Egypt as well. This was supposedly the normal procedure in cases of excommunication. However, that was easier said than done. Apparently, Ben al-Qābisī had strong and resolute friends and allies even in Alexandria. According to the letter sent from Alexandria to Cairo and found in the Cairo Geniza, a letter which is the only source of information about this incident, several of Ben al-Qābisī’s allies warned that if the local judge excommunicated him, he would apostatise. This threat seemed to have worked, at least temporarily: we are told that the local judge, although receiving full information on Ben alQābisī having already been excommunicated in several places, was hesitant to reiterate the excommunication. Allegedly he wrote to ‘our master’ in Cairo, the head of all