Many scholars of Islamic studies acknowledge the importance of Ibāḍī sources to the early history of Islam: as a sectarian group that holds distinctive perspectives on Islam vis-a-vis their Sunnī and Shi‘ite brethren, Ibāḍī texts often preserve unique views on early Islamic history, theology and law. In the work under review, Madelung and Al-Salimi provide a critical Arabic edition of six previously unpublished early Ibāḍī theological works by Abū Muḥammad ʿAbdullāh b. Yazīd al-Fazārī (d. after 179/795), an early Ibāḍī thinker of considerable importance. In fact, Early Ibāḍī Theology represents a capstone of sorts for Professor Madelung, whose interest in al-Fazārī dates back to his critical edition of the Zaydī Imām Aḥmad al-Nāṣir li-Dīn Allāh's (d. 322/934) refutation in the Kitāb al-Najāt of a treatise on predestination by al-Fazārī (Streitschrift des Zaiditenimams: Wider die Ibaditische Prädestinationslehre, Wiesbaden, 1985). Similarly, the book reflects Al-Salimi's ongoing work in publishing previously unpublished Ibāḍī manuscripts, as well as in Islamic theology. Along with al-Fazārī’s edited texts – the Kitāb al-Qadar (Book of Predetermination); Kitāb fīʾl-Radd ʿalā Ibn ʿUmayr (Refutation of Ibn ʿUmayr); Kitāb al-Radd ʿalā al-Mujassima (Refutation of the Corporalists); Kitāb al-Futyā (Book of Legal Opinion); Kitāb al-Tawḥīd fī Maʿrifat Allāh (Book of Monotheism in the Recognition of God); and the Kitāb fī man Rajaʿa ʿan ʿIlmihi wa Faraqa al-Nabī wa huwa ʿalā Dīnihi (Book about Whoever Reneges on his Knowledge and Departs from the Prophet while Remaining in his Religion) – the editors supply a short ten-page introduction (in English) discussing the works and their author, as well as providing a list and description of the manuscripts consulted for the edition. Several helpful Arabic indices (fahāris) accompany the work's end, making the edition quite useful as a tool for research.

Along with ʿĪsā b. ʿUmayr, Abū Muḥammad ʿAbdullāh b. Yazīd al-Fazārī was, for Ibāḍīs of the Maghrib (and especially for the minority community known as the Nukkār), one of the most – if not the most – important early Ibāḍī theologians. Originally from Kufa, where he corresponded with and met Maghribī Ibāḍīs who wrote or came to visit him, al-Fazārī moved to Baghdad in 169/786 where he participated in the theological circles surrounding Barmakid wazīr Yaḥyā b. Khālid (pp. 1–2). However, when the ʿAbbāsid Caliph Hārūn al-Rashīd began persecuting deviant theologians in 179/795, al-Fazārī found refuge with the Ibāḍī community in the Yemen, where he became known by the name al-Baghdādī and penned the treatise against the Qadariyya that was later refuted by Imam Aḥmad al-Nāṣir li-Dīn Allāh. Although al-Fazārī's writings made scant impact on Omani Ibāḍism (where Ibāḍī scholars resisted rationalist theology until the latter half of the third/ninth century), his influence among the Nukkārī Ibāḍīs of the Maghrib remained considerable. The Nukkār, or “Deniers”, contested the succession of ‘Abd al-Wahhāb to the Imamate of his father, ʿAbd al-Raḥmān b. Rustum (i.e. founder of the Rustumid Ibāḍī dynasty in North Africa), and followed instead Yazīd b. Fandīn. In theology, the Nukkār looked to al-Fazārī (p. 2), and preserved his memory down to the present. Indeed, the manuscripts that provide the sources for Early Ibāḍī Theology come from an Ibāḍī library in the Mzāb in Algeria. Both were copied from original texts that were located on the island of Jerba, Tunis, the heartland of the Nukkārī Ibāḍī community (pp. 8–9).

Although often fragmented or broken, the texts themselves treat an array of early theological (and even legal) topics, from God's predetermination of events (qadar) to the issue of anthropomorphism (tashbīh) to the necessity of the Imamate. Of particular interest to students of Islamic theology will be the discussion in the Kitāb al-Tawḥīd of God's attributes (sifāt) and names (asmāʾ), which al-Fazārī classifies according to whether they are attributes of essence, of act, or are shared attributes of both essence and act. As Madelung and al-Salimi note, the intricacy of al-Fazārī’s discussion of attributes of essence and acts suggests that such discussions developed far earlier in Islamic theology than is commonly assumed, i.e. before the Muʿtazilite thinkers Abū al-Hudhayl Muḥammad b. al-Hudhayl al-ʿAllāf (d. c. 235/850) and Abū Isḥāq Ibrāhīm b. Sayyār al-Naẓẓam (d. between 220/835 and 230/845), to whom the first discussion of God's attributes is commonly attributed (p. 6). Similarly, students of rational theology will find in al-Fazārī's Kitāb al-Qadar an early and detailed critique of the Qadariyya, complete with instructions of his Maghribī followers on how to refute Muʿtazilite arguments.

Unsurprisingly, many of the texts deal with topics of specific interest to early Ibāḍīs, such as determining the nature of faith and unfaithfulness (imān and kufr), providing guidelines for the practice of association (walāya), dissociation (barāʾa), or abstention from judgement (wuqūf), as well as defining the “abode” (dār) in which such activities should properly take place. Those unfamiliar with specifically Ibāḍī theological concerns might do well to consult Hoffman's Essentials of Ibāḍī Islam (Syracuse, 2012) or Cuperly's Introduction à l'étude de l'Ibadisme et de sa théologie (Algiers, 1991).

As interest in the Ibāḍiyya continues to grow, the need for reliably edited Ibāḍī sources increases. Following their earlier publication of the works of the early Omani Ibāḍī jurist, theologian and scholar Abū al-Mundhir Bashīr b. Muḥammad b. Maḥbūb (Early Ibāḍī Literature, Wiesbaden, 2011) Al-Salimi and Madelung's new preparation of al-Fazārī's kalām texts are a welcome addition to the growing library of early Ibāḍī sources. In addition, such a large collection of early kalām materials illumines in significant ways not only the development of Ibāḍī thought, but the progression of early Islamic theology in general. It is to be hoped that more scholars will follow in the footsteps of the editors, bringing the truly vast and important corpus of Ibāḍī texts to ever wider audiences.