Majma al-Zawaid — Hadith 9312

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: Whenever the Prophet (peace and blessings be upon him) appointed someone as the commander of an army, he would call him and command him to have taqwa (fear) of Allah Almighty and to treat his fellow Muslims well. Then he would instruct: "Fight in the name of Allah, and fight those who disbelieve in Allah. Do not steal from the spoils, do not break covenants, do not mutilate, and do not kill any child. When you meet your enemy from among the polytheists, invite them to one of three things. Invite them to Islam; if they accept it from you, accept it from them and refrain from fighting them. Then invite them to emigrate, (telling them) that they will have whatever the emigrants (Muhajirun) have, and the obligations that are upon the emigrants will be upon them too. If they accept this from you, accept it from them and refrain from them. If they do not do so, tell them that their position will be like that of the Bedouin Muslims: they will receive nothing from the fay' or the spoils of war, but the ruling of Allah that applies to the Muslims will apply to them. If they (the enemy) want you to let them surrender on the judgement of Allah, do not do so, for you do not know whether or not you will carry out Allah's judgement concerning them; rather, let them surrender on your own judgement. And if they want you to give them the protection (covenant) of Allah, do not do so; rather, give them your own protection and that of your companions, for if you violate the protection given by you or by your companions, that is better than violating the protection of Allah."
Al-Bazzar recorded it; its chain contains Salim bin Abd al-Wahid al-Muradi, whom Ibn Hibban declared thiqah (trustworthy) and Yahya bin Ma'in declared da'if (weak). The remaining hadiths related to this chapter will come in the chapter on those whom it is forbidden to kill during war.