Overall meaning : The Almighty mentions that the idolaters who associate partners with Him say to the Prophet, may Allah bless him and grant him peace, and his followers: When will the divine punishment with which you threaten us take place if you are telling the truth?
In response to this, Allah instructs him to say to them, 'I have no power to harm or benefit even myself except as Allah wills, nor can I possibly bring the punishment you have asked for upon you. An appointed time has been set for every nation; and when they reach their appointed time, they can neither delay it by a single hour nor put it forward.’ 'Tell me,’ He further directs him to say to them, 'should Allah’s punishment come upon you by night or day, which part of it would the evildoers then try to hasten, as all of it will be evil itself which they will not be able to escape?! And then, when it actually comes about, will you believe when faith will not then avail you? “Now do you believe,' it will be then said to them, 'and wish it far from you, when you previously denied it and desired it should be hastened?!'’
The Almighty then states that on the Day of Resurrection it will be said to those who have wronged themselves because of their unbelief: Taste the torment of eternity. Have you been repaid for anything other than what you did in the life of the world?
Then, addressing His Prophet, may Allah bless him and grant him peace, He says to him: The idolaters sarcastically ask you, 'Is the punishment you have warned us of true?’ 'say to them,’ He instructs him to tell them, 'I swear by my Lord it is certainly true. There is no doubt about it, and you will not able to escape it, for He has absolute power over you.’