Abd Allah al-Radi

Abu ʿAlī al-Ḥusayn ibn Aḥmad ibn ʿAbd Allāh ibn Muḥammad ibn Ismāʿīl (ابو علي الحسين بن أحمد ٱبْن عَبْد ٱللَّٰه ٱبْن مُحَمَّد ٱبْن إسْماعِيل, c. 825 – 881), also known as al-Zakī (lit. 'the pure'), al-Raḍī (lit. 'the satisfied one') and al-Muqtadā al-Hādī (lit. 'whose example should be followed, and guiding'), was a descendant of the Islamic prophet Muhammad and the tenth of the Isma'ili Imams, succeeding his father, Muhammad al-Taqi. Before his death in 881, he entrusted the care of his son and successor, Abd Allah al-Mahdi who was then around 8 years old to his full brother, Sa'id al-Khayr, also known as Abu'l-Shalaghlagh.

With the death of Ja'far al-Sadiq in 148/765, Isma'il and Muhammad, the gravity of persecutions of the Abbasids had considerably increased. The Isma'ili Imams were impelled to thicken their hiding, therefore, the first dawr al-satr came into force from 197/813 to 268/882, wherein the Imams were known as al-a'imma al-masturin (lit. 'the concealed Imams'). The concealment ended with the establishment of the Fatimid caliphate ((r. 909 – 1171)).

Historical background
With the death of Ja'far al-Sadiq in 148/765, Isma'il and Muhammad, the gravity of persecutions of the Abbasids had considerably increased. The Isma'ili Imams were impelled to thicken their hiding, therefore, the first dawr al-satr ('period of concealment') came into force from 197/813 to 268/882, wherein the Imams were known as al-a'imma al-masturin (lit. 'the concealed Imams'). During this time, the living Imam's identity was hidden for protection and the community continued to operate under the authority of Muhammad ibn Isma'il. According to later tradition, these were Abd Allah (the 8th Imam), Ahmad (the 9th Imam) and al-Husayn (the 10th Imam). Among the later Isma'ili historians, Ahmad ibn Ibrahim al-Naysaburi, the author of Istitār al-Imām, compiled under the Fatimid Imam–Caliph al-Aziz Billah ((r. 975 – 995)) seems first to have mentioned the names of the three 'hidden' Imams.

Modern historian of the Fatimid period, Shainool Jiwa, explains that during dawr al-satr (765–909 CE) Ismaili doctrine had spread as far as from Yemen to Ifriqiya (modern-day Tunisia and eastern Algeria), with its most prominent adherents being the Kutama Berbers of North Africa.

Life
Husayn ibn Ahmad was born in 825 and assumed the Imamate in 840. His hujjat was Ahmad, surnamed al-Hakim, a descendant of Husayn ibn Ali, to whom Abd Allah ibn Maymun al-Qaddah handed over his position. Al-Radi's headquarters continued in Salamiyah, where he was among the Hashimites and appeared to be one of them. He gave presents to the local governors and was lavish with hospitality. He is said to have granted allowances from his wealth to the poor and disabled persons in Salamiyah without discrimination between the Isma'ilis and non-Isma'ilis. If the name of his father Muhammad al-Taqi is remembered through the Encyclopedia of the Brethren of Purity (Rasāʿil Ikhwān al-ṣafā), which the son is said to have summarized in his Jāmiʿat al-Jāmiʿa, al-Radi is connected with a spreading daʿwah or propaganda."He organised the propaganda, spread it further afield, broadcast instruction to his followers, making it manifest; he established proofs, explained the risalas (apparently the Encyclopedia of the Ikhwān al-ṣafā') and despatched his da'is everywhere. He thus made the true religion visible to those who were in search of it."Al-Radi travelled to Kufa, on pilgrimage to the tombs of Ali ibn Abi Talib and his son, Husayn. While there he met and became attached to Abu al-Qasim ibn Hasan ibn Farah ibn Hawshab, who was of the Twelvers and was associated with Hasan al-Askari; and also to Ali ibn al-Fadl al-Jayshani, both of whom he sent to Yemen to establish the way of the Isma'iliyya there. They reached Yemen, and conquered Sanaa, the capital of Yemen, and exiled the ruling tribe of Banu Laydir, and established Isma'ili authority in Yemen.

Al-Radi died in 268/881 at Salamiyah while he was travelling in the vicinity, appointing before his death as his trustee his own brother, Sa'id al-Khayr, also known as Abu'l-Shalaghlagh, as the guardian of his son, al-Mahdi. It is stated in the Istitār al-Imām that the guardian, Abu'l-Shalaghlagh, the 'acting Imam', tried to usurp the Imamate for his own line, appointing one after another his sons successively as his heir, but that all of these died, so that ultimately the Imamate, by the will of God, returned to him for whom it was destined, i.e. al-Mahdi. Al-Radi's death in 268/881 marked the termination of dawr al-satr in the Isma'ili history.