وَإِن كُنتُم في رَيبٍ مِمّا نَزَّلنا عَلىٰ عَبدِنا فَأتوا بِسورَةٍ مِن مِثلِهِ وَادعوا شُهَداءَكُم مِن دونِ اللَّهِ إِن كُنتُم صادِقينَ

If you doubt what We revealed to Our servant, produce a chapter like it, and call upon your witnesses, other than God, if you are indeed truthful.