Quran

“And if ye are in doubt as to what We have revealed from time to time to Our servant, then produce a Sura like thereunto; and call your witnesses or helpers (If there are any) besides Allah, if your (doubts) are true. But if ye cannot- and of a surety ye cannot- then fear the Fire whose fuel is men and stones,- which is prepared for those who reject Faith. “2:23&24

Indeed, it probably is no exaggeration to say that the Qur’an was one of the most conspicuous forces in the making of classical and post-classical Arabic literature. It is the Holy book of Muslims. The religious scripture in Islam.

Some modern Western historians have concluded that Muhammad was sincere in his claim of receiving revelation, “for this alone makes credible the development of a great religion.” [25] Modern historians generally decline to address the further question of whether the messages Muhammad reported being revealed to him were from “his unconscious, the collective unconscious functioning in him, or from some divine source”, but they acknowledge that the material came from “beyond his conscious mind” [26]

According to the Qur’ān:

"This Qur'ān is not such as can be produced by other than Allah; on the contrary it is a confirmation of (revelations) that went before it, and a fuller explanation of the Book - wherein there is no doubt - from the Lord of the worlds. Or do they say, "He forged it"? Say: "Bring then a Sura like unto it, and call (to your aid) anyone you can besides Allah, if it be ye speak the truth!"10:37&38