The two sermons edited and translated here for the first time are primary material from the years before the establishment of the Fatimid caliphate in 297/909. The authors have been identified as Abu 'Abd Allah al-Shi'i and Abu'l-'Abbas Muhammad, two brothers who were central to the success of the Ismaili da'wa in North Africa. Da'wa, a term used to describe how Muslims teach others about the beliefs and practices of their Islamic faith, therefore provide a unique view of the nature and development of Islam throughout history. In this case, the primary texts shed light on the development of Islam among the Berbers of the Maghreb.

The first text by Abu 'Abd Allah al-Shi'i shows how the arguments for belief in the 'imamate' of the family of the Prophet, that is, the Shi'a belief that all imams should be spiritual descendants of the Prophet Muhammad and his household, were developed and presented to bring new adherents to the cause. The Book of the Keys to Grace by his elder brother Abu'l-'Abbas, too, concerns not only the centrality of the imam in the faith but also sheds light on the hierarchy of the da'wa in this early period and its organisational sophistication.

Both texts also reveal the contemporary theology propagated by the Ismaili da'wa, including for instance, the powerful analogy of Moses/Aaron and Muhammad/'Ali, the awareness of a variety of religious traditions and the use of detailed Qur'anic quotations and a wide range of hadith. As such they constitute primary source material of interest not only for Ismaili history but for this early period of Islam in general.

In Ibāḍī Texts from the 2nd/8th Century Abdulrahman Al-Salimi and Wilferd Madelung present an edition of fourteen Ibāḍī religious texts and explain their contents and extraordinary source value for the early history of Islam. The Ibāḍīs constitutes the moderate wing of the Kharijite opposition movement to the Umayyad and ‘Abbasid caliphates. The texts edited are mostly polemical letters to opponents or exhortatory to followers by ‘Abd Allah b. Ibad , Abu l-‘Ubayda Muslim b. Abi Karima and other Ibadi leaders in Basra, Oman and Hadramawt. An epistle detailing the offences of the caliph ‘Uthman is by the early Kufan historiographer al-Haytham b. ‘Adi. By their early date and independence of the mainstream historical tradition these txts offer the modern historian of Islam an invaluable complement to the well-known literary sources.

The volume contains critical editions of the extant parts of two hitherto unknown theological works by the Būyid vizier al-Ṣāḥib b. ʿAbbād (d. 385/925), who is well known to have vigorously promoted the teaching of Muʿtazilī theology throughout Būyid territories and beyond. The manuscripts on which the edition is based come from Cairo Geniza store rooms. They consist of two manuscripts for each of the two texts—testimony to the impact of al-Ṣāḥib’s education policy on the contemporaneous Jewish community in Cairo. The longer treatise of al-Ṣāḥib of ca. 350/960, possibly his Kitāb Nahj al-sabīl fī uṣūl al-dīn, appears to be the earliest Muʿtazilī work preserved among the Jewish community. The second, briefer treatise also contains a commentary by ʿAbd al-Jabbār al-Hamadānī (d. 415/1025).