(And We shall take out from every nation a witness) a prophet who will testify against them, i.e. that he conveyed the message to them; this prophet is the prophet who was sent to them in the life of the world (and We shall say: Bring your proof) why did you reject the messengers? (Then they will know) each nation will know (that Allah hath the Truth) that the worship of Allah and the religion of Allah are the Truth, and that their judgement is up to Allah, (and all that they invented) all that which they falsely worshipped (will have failed them) will become too preoccupied with themselves to help them.