Now when ye meet those who disbelieve, smite their necks until when ye have slain them greatly, then make fast the bonds; then, thereafter let them off either freely or by ransom, until the war layeth down the burthens thereof. That ye shall do. And had Allah willed, He would have vindicated Himself against them, but He ordained fighting in order that He may prove you one by the other. And those who are slain in the way of Allah, He shall not send their works astray.