Allah mentions the blessing and great bounty that He has bestowed upon His servant and Messenger Muhammad by revealing to Him the Noble Qur'an to which falsehood cannot come, from before it or behind it, (it is) sent down by the All-Wise, Worthy of all praise. Ibn Mas'ud said, "A red wind will come to the people, meaning at the end of time, from the direction of Syria, and there will be nothing left in a man's Mushaf (copy of the Qur'an) or in his heart, not even one Ayah." Then Ibn Mas'ud recited:

Challenging by the Qur'an

Then Allah points out the great virtue of the Qur'an, and says that even if mankind and the Jinn were all to come together and agree to produce something like that which was revealed to His Messenger they would never be able to do it, even if they were to cooperate and support and help one another. This is something which is impossible. How could the words of created beings be like the Words of the Creator Who has no equal and peer, for there is none like unto Him?

meaning, 'We have furnished them with evidence and definitive proof, and We have shown them the truth and explained it in detail, yet despite that most of mankind insist on disbelief, i.e., denying and rejecting the truth.'