Revelation, if you are in doubt

And if you are in doubt about what We have sent down [i.e., the Qur’ān] upon Our Servant [i.e., Prophet Muḥammad (ﷺ)], then produce a sūrah the like thereof and call upon your witnesses [i.e., supporters] other than Allāh, if you should be truthful.

But if you do not - and you will never be able to - then fear the Fire, whose fuel is people and stones, prepared for the disbelievers.