'Abd Allah b. Yazid al-Fazari (2nd/8th century) was one of the leading early Islamic theologians. His works are still among the most reliable and accessible to scholars and this text is a significant new addition to al Fazari's texts that were previously published (IHC. 104/IHC. 182). This present study is based on a discussion of al-Fazari's teachings with the title Kitab fi al-Tawhid, which is a commentary on his lost work by an anonymous North African Ibadi theologian and is unique because it is among the few known works which describe the doctrine of the early Ibadis. The addition of this text to al -Fazari's previously discovered writings provides us with further information about the early Ibadis' theological views; more importantly, however, it also enables us to trace the development of the terminology they used and understand how and why it changed, as well as the intellectual aspects of the Islamic theological debates during the 2nd/8th century. This study successfully establishes that the opinions of this Ibadi school of theology have remained the same from one generation to the next - among the eastern Ibadis in Oman, Yemen and Hadhramawt as well as the western Ibadis in North Africa. It refutes previous speculation which maintained that al Fazari's views were on the decline in Ibadi circles from the middle of the 5th/11th century, since the evidence shows that the precise opposite was the case. In fact, this study shows that his theological teachings were still being followed in the 20th century by the Ibadis in Oman and North Africa.