Musannaf Ibn Abi Shayba 28:1003

Waki' narrated to us, he said: Sufyan narrated to us, from Alqama bin Marthad, from Sulayman bin Burayda, from his father, who said: When the Messenger of Allah (may Allah bless him and grant him peace) would send a commander over a raiding party or an army, he would say: "Do not commit ghulul (treachery/stealing from the spoils of war)."