In the last three verses (15-17), there is the refutation of a false notion entertained by the deniers of Akhirah and also the rejection of an inappropriate request made by them. They were a people who did not know much about God or Revelation or Prophets sent by Him. They took them to be like common human beings having nothing special about them. Think of the Holy Qur'an, which reached the world through the Prophet of Islam. Even this, they thought, was spoken and written by him. It was under this frame of mind that they told the Holy Prophet ﷺ ` as for this Qur'an, it is against our beliefs and ideas.' These idols our forefathers have been worshipping since ever as providers of their needs are, according to the Qur'an, totally false and ineffectual. There are things we have been using and transactions we have been making all along. The Qur'an says that they are all unlawful. And then, the Qur'an tells us that we have to live again after we are dead and that we have to account for everything we have done. All these things make no sense to us. We are not ready to accept them. Therefore, you do one of the two things we are asking you to do. Either you replace this one with another Qur'an which does not have these things, or at the least, amend this very Qur'an and expunge those (undesirable) things from there.'
Rejecting their false notion first, the Qur'an instructs the Holy Prophet a1JI to tell those people that the Qur'an was not his Word, nor could he change it on his own. He only followed what was revealed to him by Allah. If he were to make the least change in it on his own and by his choice, he would be committing a grave sin, and that he feared the punishment that falls upon those who disobey Allah, therefore, he could not do that.
Then he was asked to tell them that he did everything under Divine orders. Had it been the will of Allah Ta` ala that this Word should not be recited to them, neither would he have recited that to them, nor would He have let them know about that. Now that it was the very will of Allah Ta` ala that they should be made to listen to precisely that Word, who can dare make any addition or deletion therein?