The main part of this book consists of a compilation and evaluation of the corpus of traditions about the life of Muhammad attributed to the early scholar 'Urwa ibn al-Zubayr (c. 643-c. 712). 'Urwa was the nephew of the Prophet's wife 'A'isa, who was also his most important informant. The authenticity of a large part of these traditions is certain, since they were handed down independently from each other by two or more tradents of 'Urwa. They are thus the oldest authentic Muslim reports about the Prophet. The authors argue that 'Urwa's reports by and large correctly reflect the basic features of the historical events described.

Somewhat older than 'Urwa's traditions about Muhammad is only a report in a non-Islamic Armenian source attributed to the chronicler Sebeos (wrote around 660). This and other external evidence partly agree with the Islamic sources, sometimes providing new perspectives on the life of the Prophet. But there are also contradictions. The authors can show that in such cases the 'Urwa transmission is preferable.

The crux of the much-discussed so-called Hagarism hypothesis, which proposes an alternative narrative of the origins of Islam (Muhammad, after having established a community which comprised both Arabs and Jews, set off with these allies to conquer Palestine) is demonstrably based on a misreading of a Sebeos passage..