Al Baqarah, 23 Ayah
2:23
وَإِن كُنتُمۡ فِي رَيۡبٖ مِّمَّا نَزَّلۡنَا عَلَىٰ عَبۡدِنَا فَأۡتُواْ بِسُورَةٖ مِّن مِّثۡلِهِۦ وَٱدۡعُواْ شُهَدَآءَكُم مِّن دُونِ ٱللَّهِ إِن كُنتُمۡ صَٰدِقِينَ ٢٣
Wa 'In Kuntum Fī Raybin Mimmā Nazzalnā `Alá `Abdinā Fa'tū Bisūratin Min Mithlihi Wa Ad`ū Shuhadā'akum Min Dūni Al-Lahi 'In Kuntum Şādiqīna
And if you are in doubt about what We have sent down upon Our Servant [Muhammad], then produce a surah the like thereof and call upon your witnesses other than Allah, if you should be truthful.