﴿ وَإِن كُنتُمْ فِى رَيْبٍۢ مِّمَّا نَزَّلْنَا عَلَىٰ عَبْدِنَا فَأْتُوا۟ بِسُورَةٍۢ مِّن مِّثْلِهِۦ وَٱدْعُوا۟ شُهَدَآءَكُم مِّن دُونِ ٱللَّهِ إِن كُنتُمْ صَٰدِقِينَ ﴾

“And if you doubt any part of what We have, bestowed from on high, step by step, upon Our servant [Muhammad], then produce a surah of similar merit, and call upon any other than God to bear witness for you -if what you say is true!”

(And if ye are in doubt concerning that which We revealed) through the Archangel Gabriel (unto Our slave) Muhammad whom you accuse of fabrication, (then produce a surah like it) produce a surah like the surah of the Cow (al-Baqarah), (and call your witnesses), seek help from the gods that you worship, (apart from Allah), it is said that this refers to their leaders, (if ye are truthful) in your claim.