ولا يقسم السبى منهم وإن إحتاج الناس إليه ما لم يخرجوهم إلى دار الاسلام ولا يبيعهم ويمشيهم حتى يخرجوهم إلى دار الاسلام إن أطاقوا المشى وإن لم يطيقوه ولم يكن معه فضل حمولة ولم تطب أنفس من معه فضل حمولة من أهل العسكر بحملهم عليه قتل الرجال وترك النساء والصبيان
كتاب السير الصغير للشيباني ٣٥
Those of them taken as prisoners are not apportioned, even if people need them, as long as they have not yet been brought into Islamic territory [Dar Al-Islam]. He must not sell them, but make them march until they have brought them into Dar Al-Islam, provided they can make the trek. If they can not make it, and he does not have extra transport, and none of those with him who have extra transport is of a mind to take them, then the men are killed and the women and children are left.
Al-Shaybani, Kitab Al-siyar Al-saghir [The Lesser Book on Campaigns], item 35