Muhammad 47:4 فاذا لقيتم الذين كفروا فضرب الرقاب حتى اذا اثخنتموهم فشدوا الوثاق فاما منا بعد واما فداء حتى تضع الحرب اوزارها ذالك ولو يشاء الله لانتصر منهم ولاكن ليبلو بعضكم ببعض والذين قتلوا في سبيل الله فلن يضل اعمالهم ٤

Therefore, when ye meet the Unbelievers (in fight), smite at their necks; At length, when ye have thoroughly subdued them, bind a bond firmly (on them): thereafter (is the time for) either generosity or ransom: Until the war lays down its burdens. Thus (are ye commanded): but if it had been Allah's Will, He could certainly have exacted retribution from them (Himself); but (He lets you fight) in order to test you, some with others. But those who are slain in the Way of Allah,- He will never let their deeds be lost.