Surat Hud (13-14)

{أَمْ يَقُولُونَ افْتَرَاهُ قُلْ فَأْتُواْ بِعَشْرِ سُوَرٍ مِّثْلِهِ مُفْتَرَيَاتٍ وَادْعُواْ مَنِ اسْتَطَعْتُم مِّن دُونِ اللّهِ إِن كُنتُمْ صَادِقِينَ} (هود : 13)

13- Did polytheists claim that Muhammad (peace be upon him) had made the Qur'an by himself and it was not a revelation from Allah? O Messenger, say to them: If the matter is as you said, bring ten Surahs of the like in its eloquence, well-organization, and precise meanings, for you are human like me and the words of Arabic language are easily-accessed for you as they are for me. Furthermore, you may seek the help of your eloquent people and foretellers either from humans or Jinns to bring something of the like if you are truthful that I had composed the Qur'an.

{فَإِن لَّمْ يَسْتَجِيبُواْ لَكُمْ فَاعْلَمُواْ أَنَّمَا أُنزِلِ بِعِلْمِ اللّهِ وَأَن لاَّ إِلَـهَ إِلاَّ هُوَ فَهَلْ أَنتُم مُّسْلِمُونَ} (هود : 14)

14- If the haughty polytheists did not respond to you and did not bring something like the Qur'an or even ten Surahs of it, let it be known to all that the Qur'an is the words of Allah which He revealed to His Messenger Muhammad (peace be upon him). The words of the Qur'an are miraculous and no one is able to bring something of the like until the end of time. Let it be known that Allah is One and has no associate in worship. O polytheists, your gods are not associate to Allah, and if they are true partners to Allah, they will help you is opposing the Messenger of Allah. So, would you embrace Islam after failing in this plain challenge?