And He it is Who has made you successors in the land and raised some of you above others by (various) grades, that He might try you by what He has given you; surely your Lord is quick to requite (evil), and He is most surely the Forgiving, the Merciful.

So when you meet in battle those who disbelieve, then smite the necks until when you have overcome them, then make (them) prisoners, and afterwards either set them free as a favor or let them ransom (themselves) until the war terminates. That (shall be so); and if Allah had pleased He would certainly have exacted what is due from them, but that He may try some of you by means of others; and (as for) those who are slain in the way of Allah, He will by no means allow their deeds to perish.