Allah tells us about the obstinance of the disbelievers of the Quraysh, who were opposed to the message and denied Allah. When the Messenger read to them from the Book of Allah and His clear evidence they said to him: "Bring a Qur'an other than this.'' They wanted the Prophet to take back this Book and bring them another book of a different style or change it to a different form. So Allah said to His Prophet :

﴿قُلْ مَا يَكُونُ لِى أَنْ أُبَدِّلَهُ مِن تِلْقَآءِ نَفْسِى﴾

(Say: "It is not for me to change it on my own accord;) This means that it is not up to me to do such a thing. I am but a servant who receives commands. I am a Messenger conveying from Allah.

﴿إِنْ أَتَّبِعُ إِلاَّ مَا يُوحَى إِلَىَّ إِنِّى أَخَافُ إِنْ عَصَيْتُ رَبِّى عَذَابَ يَوْمٍ عَظِيمٍ﴾

(I only follow that which is revealed unto me. Verily, I fear the torment of the Great Day (the Day of Resurrection) if I were to disobey my Lord.)