Surah 42. Ash-Shura, Ayah 18

This is not merely a reference to the sarcastic demand of Muhammad's opponents (mentioned several times in the Qur'an) to bring about their "speedy chastisement" in proof of his being God's message-bearer, but also an oblique allusion to unbelievers of all times who, without having any "proof" either way, categorically reject the idea of resurrection and judgment.

The Unbelievers do not believe in Judgment and laugh at it. They say defiantly, "If there is to be a punishment, let it come at once!" The threefold answer to this will be found in n. 1810 to xiii. 6. With those who believe, the case is different. They know that the Hereafter is an awful Reality, and prepare for it. They see clearly on what a wrong track the scoffers are!