So these ḥadiths show that the Jewish scholars—such as ʿAbd Allah ibn Salām and others—used to ask him questions about issues of which they said, “No one knows them except a prophet,” that is, or someone who has learnt them from the prophets. The questioners themselves already possessed that knowledge, as is also reported in the wording: “No one knows them except a prophet, or one man, or two men.”
They would therefore test him with these questions to see whether he knew them; and if he did know something that only a prophet could know, then he was indeed a prophet. It is obvious, however, that their purpose could only be fulfilled if they were certain that he had not learnt those matters from any of the People of the Scripture—or from someone who had studied under them—for it is well known that some people had acquired such knowledge, but they had obtained it from the prophets.
This makes it clear that those interrogators from among the People of the Scripture were convinced that no human being had taught him what the People of the Scripture possessed of knowledge. Had they deemed it possible that he had learnt what only a prophet knows from the People of the Scripture, he would have been like them, and his knowledge of those matters and his answers would not have been proof of his prophethood.
Consequently, those questioners had to be absolutely certain that he had not learnt from any of the People