And the Exalted One said:

“Or do they say, ‘He has fabricated it’? No indeed; they simply will not believe. Let them, then, bring a discourse like it, if they are truthful.” (al-Ṭūr 33)

He, exalted be He, also said:

“Or do they say, ‘He has forged it’? Say, ‘Produce ten surahs like it—fabricated if you wish—and call on whomever you can besides Allah, if you are truthful. But if they fail to respond to you, then know that it has been sent down with Allah’s knowledge, and that there is no god but Him. Will you not then submit?’” (Hūd 13–14)

And He, exalted be He, said:

“If you are in doubt about what We have sent down to Our servant, then produce a single surah like it and call your witnesses besides Allah, if you are truthful. But if you do not—and you will never do so—then guard yourselves against the Fire whose fuel is people and stones, prepared for the disbelievers.” (al-Baqarah 23–24)