Say to those of the dwellers of the desert who were left behind: You shall soon be invited (to fight) against a people possessing mighty prowess; you will fight against them until they submit; then if you obey, Allah will grant you a good reward; and if you turn back as you turned back before, He will punish you with a painful punishment.

And what reason have you that you should not spend in Allah's way? And Allah's is the inheritance of the heavens and the earth, not alike among you are those who spent before the victory and fought (and those who did not): they are more exalted in rank than those who spent and fought afterwards; and Allah has promised good to all; and Allah is Aware of what you do.