he himself acknowledges to be from Allah—how could he not be one who denies the very foundation of prophethood?!

Next, Allah confronted them with the fact that through revelation they learned matters unknown to them and to their forefathers; had it not been for the revelation Allah sent to His prophets and messengers, they would never have reached such knowledge. He then ordered His Messenger to reply to the question, “Who sent down the Book that Moses brought?” by saying, “Say: Allah,” meaning: Allah alone sent it down. That is, even if they disbelieve and deny it, you, O Prophet, must believe in it and affirm it, then leave them to plunge about in their idle talk, playing (91).

The answer to this challenge is that Allah, exalted is He, argued against them with what the adherents of the two previous Scriptures admit—the people of knowledge as opposed to nations that possess no book. In other words: If you deny the root of prophethood and claim that Allah has never revealed anything to a human being, then here is the Book of Moses, acknowledged by the People of the Scripture, who are more learned than you; so ask them about it.

There are many similar instances in the Quran where the Almighty calls the People of the Scripture to testify against those who reject prophethoods and monotheism.

Thus the meaning is: If you deny that Allah ever sent anything down to a human being, then who sent down the Book of Moses? And if you do not know, ask the People of the Scripture.

As for His words, “You turn it into parchments, displaying them while concealing much,” those who read the verb in the third-person form understand it as a report about the Jews in the absent tense, whereas those who read it in the second-person form (1) take it as an address to this very group (2) who behaved in that manner—namely, you to whom the Book was revealed, treating it in that way.