Musnad Ahmad 626:20

Abu Mu'awiyah narrated to us, Hisham ibn 'Urwah narrated to us, from his father, from al-Mughirah ibn Shu'bah, that he accompanied a group of polytheists and found them in a state of negligence, so he killed them and took their wealth. He then brought it to the Prophet, peace and blessings of Allah be upon him, but the Messenger of Allah, peace and blessings of Allah be upon him, refused to accept it.