That is: “it could not possibly have been fabricated,” meaning, “no one was ever able to do such a thing.” Thus He did not merely deny the act itself; He denied even the possibility of the act and declared that something of this kind never occurs—indeed, its occurrence is impossible. The sense, then, is that it is neither possible nor conceivable nor permissible for this Qur’an to be forged by anyone other than Allah. For whoever would attempt to fabricate it apart from Allah is a created being, and a created being has no power to do so.

This challenge was first issued in Mecca, for the surahs in question—Yunus, Hud, and al-Tur—are all Meccan. He later renewed the challenge in Medina after the Hijrah, when He said in al-Baqarah, a Medinan surah:

“If you are in doubt about what We have sent down to Our servant, then bring a surah like it, and call upon your witnesses other than Allah, if you are truthful.” ⦗al-Baqarah 23⦘

Then He said:

“But if you do not—and you will never be able to—then guard yourselves against the Fire whose fuel is people and stones.” ⦗al-Baqarah 24⦘

Thus He mentioned two matters, the first of which is His statement: “But if you do not—and you will never be able to—then guard yourselves against the Fire…” ⦗al-Baqarah 24⦘.