It was narrated that Safwan bin ‘Assil said:“The Messenger of Allah (ﷺ) sent us in a military detachment and said: ‘Go in the Name of Allah, and in the cause of Allah. Fight those who disbelieve in Allah. Do not mutilate, do not be treacherous, do not steal from the spoils of war, and do not kill children.’”

English translation · Sunan Ibn Majah