“Abu Hatim ar-Razi was followed by Abu Abdullah Muhammad bin Ahmad an-Nasafi and Abu Yaqub as-Sijistani staying at Ray. An-Nasafi operated the mission mostly in Khorasan and Bukhara, and gained great success in converting the Sunni ruler, Nasr bin Ahmad, who had given allegiance to Imam al-Mahdi and paid him an annual tribute of 119 thousand dinars. Nasr bin Ahmad also entered into correspondence with Imam al-Qaim in Maghrib.
The renowned poet and intellect, Abu Abdullah bin Jafar bin Muhammad bin Hakim bin Abdur Rahman bin Adam ar-Rudaki ash-Shair as-Samarkandi, known as Rudaki (d. 329/940) also found an opportunity of espousing Ismaili faith in this period. He was a court poet of the Samanids, and composed many verses in praise of the Fatimid Imams. In one place, Maruf of Balkh, one of the earliest Samanid poets, says: “I have heard the king of poets, Rudaki as saying, `do not give allegiance to anyone save the Fatimids.'”
The Abbasids took notice of the rapid conversion of the Ismailis in Khorasan, notably Nasr bin Ahmad, and insinuated Nuh bin Nasr (331-343/943-954), the son of Nasr bin Ahmad; against his father and the Ismailis. Nuh bin Nasr dethroned his father and conducted a barbarous massacre of the Ismailis in 331/942, known in the Ismaili history as al-mainat al-uzama (great calamity) in Khorasan and Transoxania. An-Nasafi and his chief associates were also executed in the wild operations at Bukhara in 332/943. For this reason, Nasir Khusaro called him Khwaj-i Shahid and Shaikh al-Shahid. It resulted a setback in Ismaili mission, but was resumed under an-Nasafi’s son, Masud, surnamed Dihqan and Abu Yaqub as-Sijistani. An-Nasafi is considered a leading Ismaili philosopher among the early Ismailis. He produced a major work, entitled Kitab al-Mahsul (Book of the Yield). Paul E. Walker writes in Abu Yaqub al-Sijistani: Intellectual Missionary (London, 1996, pp. 17-18) that, “So influential were al-Nasafi and this one book that, throughout the rest of the century, writers both in and outside the Ismaili fold referred to it as if it represented the intellectual heart of Ismailism.”