As for what Muslims need to know, Allah has provided evidence establishing the truth concerning it. Examples of matters that offer no benefit and for which there is no evidence establishing the correct view include their disagreements about the colour of the dog belonging to the Companions of the Cave, which part of the cow Moses struck with, the dimensions of Noah’s ark and the wood from which it was made, the name of the boy whom al-Khidr killed, and similar matters.

Such matters can be known only through transmitted reports. Whatever has been authentically transmitted from the Prophet, may Allah bless him and grant him peace—such as the fact that Moses’ companion was named al-Khidr—is therefore known. Whatever has not been transmitted in this way, but instead comes from the People of the Book—such as reports transmitted by Kaʿb, Wahb, Muhammad ibn Ishāq, and others who relate material from the People of the Book—may neither be affirmed nor denied without evidence. As authentically reported, the Prophet, may Allah bless him and grant him peace, said:

“When the People of the Book tell you something, neither believe them nor disbelieve them, for they may tell you something true and you reject it, or they may tell you something false and you believe it.”

The same applies to reports transmitted from some of the Successors, even when a Successor does not mention having taken the report from the People of the Book. Whenever the Successors disagree, the statements of some do not constitute authoritative evidence against those of others.

Authentically transmitted reports from some of the Companions concerning these matters inspire greater confidence than reports from some of the Successors. This is because there is a stronger possibility that the Companion heard it from the Prophet, may Allah bless him and grant him peace, or from someone who heard it from him, and because the Companions transmitted less from the People of the Book than the Successors did. Moreover, given the firm conviction of