Abu l-Mundhir Bashir b. Muhammad b. Mahbub (d. ca. 290/908) was a prominent Ibadi scholar and author of authoritative theological and legal books. His writings reflect expert knowledge of Ibadi religious law and a consistent inclination to rationalist kalam in contrast to the traditionalist tendency of earlier Ibadi scholarship in Oman. Early Ibadi Literature contains a first edition of three Arabic treatises by Abu l-Mundhir. Two of the texts, K. al-Rasf fi l-Tawhid (Book of Paving about Divine Unity) and K. al-Muharaba (Book of Warfare), were until recently considered lost by western scholars. With their discovery, a significant new source for the study of the development of early Ibadi thought in Oman has become available. The third text, Abu l-Mundhir’s so-called Sira, sets forth his legal opinion condemning the deposition of the 'Umani Ibadi Imam al-Salt b. Malik in 272/886. The edition of each of the texts is based on four out of five manuscripts kept in three private libraries in Oman, the Salimi library in Bidiyya, the Sayyid Muhammad b. Ahmad Al Bu Sa'idi library in al-Sib and the collection of Shaykh Ahmad b. Hamad al-Khalili, the recent Grand Mufti of Oman.