Those who disbelieve Our revelations, We shall expose them to the Fire. As often as their skins are consumed We shall exchange them for fresh skins that they may taste the torment. 4:56
What should those who doubt that Allah will give Muhammad victory do?
Go hang themselves
Whoso is wont to think (through envy) that Allah will not give him (Muhammad) victory in the world and the
Hereafter (and is enraged at the thought of his victory), let him stretch a rope up to the roof (of his dwelling),
and let him hang himself. 22:15
