Musnad Abu Ya'la al-Mawsili 251:4

Ahmad ibn Isa al-Tustari narrated to us, Abdullah ibn Wahb narrated to us, he said: Ibn Lahi'ah narrated to me, from Abd Rabbih ibn Sa'id, from Salamah ibn Kuhayl, from Shaqiq ibn Salamah, from Jarir ibn Abdullah al-Bajali, who said: When the Messenger of Allah (may Allah bless him and grant him peace) would send out a military expedition, he would say: "In the name of Allah, and in the way of Allah, and upon the creed of the Messenger of Allah. Do not act treacherously, do not break your pledges, do not mutilate, and do not kill children."