البقرة — Al-Baqarah Ayat 23
وَاِنْ كُنْتُمْ فِيْ رَيْبٍ مِّمَّا نَزَّلْنَا عَلٰى عَبْدِنَا فَأْتُوْا بِسُوْرَةٍ مِّنْ مِّثْلِهٖ ۖ وَادْعُوْا شُهَدَاۤءَكُمْ مِّنْ دُوْنِ اللّٰهِ اِنْ كُنْتُمْ صٰدِقِيْنَ
Wa in kuntum fī raibim mimmā nazzalnā ‘alā ‘abdinā fa'tū bisūratim mim miṡlih(ī), wad‘ū syuhadā'akum min dūnillāhi in kuntum ṣādiqīn(a).
"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."