When you meet the unbelievers (in battle), smite their necks until you have crushed them, then bind your captives firmly; thereafter (you are entitled to) set them free, either by an act of grace, or against ransom, until the war ends. That is for you to do. If Allah had so willed, He would have Himself exacted retribution from them. (But He did not do so) that He may test some of you by means of others. As for those who are slain in the way of Allah, He shall never let their works go to waste.