encouraged by the rapid progress of the , which was now establishing armed strongholds in preparation of the 's arrival—secretly declared himself to a few senior members of the not as the for Muhammad ibn Isma'il, but the actual imam; and that he claimed for his nephew Sa'id the title of , and for the latter's infant son the title of . This claim was taken up by Sa'id, although later Fatimid doctrine insisted that Sa'id's father, al-Husayn, had been a hidden imam in succession to Ahmad ibn Abdallah al-Akbar, rather than Abu'l-Shalaghlagh; the latter in turn is accused in these works of trying to usurp the position of Sa'id. Various genealogies were later put forth by the Fatimids and their followers to justify this claim, generating a heated controversy that lasts until the present day. In the most common version, Abdallah al-Akbar was proclaimed to be the son of Muhammad ibn Isma'il, but even in pro-Isma'ili sources, the succession line and names of the hidden imams who supposedly preceded Sa'id are not the same, partly due to the Isma'ili practice of using codenames and hiding their identity () to avoid persecution. Anti-Isma'ili Sunni and Twelver sources naturally rejected any Fatimid descent from Ali ibn Abi Talib altogether and considered them as impostors. The situation is further complicated by the use of the title , normally a synonym for the , for Sa'id's son. This has led to claims, already in medieval times, that Abd al-Rahman was the genuine imam, whereas Sa'id descended from a line of s and was not actually Abd al-Rahman's father nor a legitimate imam. Abu'l-Shalaghlagh died sometime after 893, and Sa'id became the head of the . In 899, the letters being sent to the senior missionaries from Salamiya revealed changes in the official doctrine of the movement. This worried Hamdan Qarmat, who sent his brother-in-law to Salamiya to investigate the matter. It was only there that Abdan learned of the new claim: that the expected, hidden imam was not Muhammad ibn Isma'il, but Sa'id himself. Upon learning of this, Hamdan denounced the leadership in Salamiya, gathered the Iraqi s and ordered them to cease the missionary effort. Shortly after he disappeared from his headquarters, and Abdan was assassinated at the instigation of Zakarawayh ibn Mihrawayh, who had remained loyal to Salamiya. These events caused a major split in the Isma'ili movement, between those who