Overall meaning :
Say, Muhammad, ‘None in the heavens and the earth knows what is hidden except Allah, nor does anyone know when Allah will raise the dead from their graves on Judgement Day.’ The idolaters’ knowledge on the Day of Resurrection will be perfect when they see the punishment with their own eyes and find out that everything they have been warned of in the life of the world is absolutely true. Indeed, they have serious doubts about the reality of the hereafter. They are in fact totally ignorant about it in this life.
The unbelievers say, ‘After we and our fathers have been reduced to dust, will we really be brought forth alive out of our graves?! This will never happen! We have been threatened with this before, both we and our fathers, but nothing of this sort has ever happened. This is nothing but fables of the ancients who had recorded them in their books!”
Say, Muhammad, to the idolaters, ‘Go about through the earth and see the final fate of the unbelievers who denied the truth and were destroyed,’ so that they may reflect and take heed. Do not grieve, Muhammad, over what could happen to them as a result of their turning away from you and rejecting your message, nor be distressed by their schemes, for Allah will protect you, give you victory over them and make His religion reign supreme