Musnad Ahmad 953:3

Yahya ibn Sa'id al-Qattan narrated to us, from Hammad ibn Salamah, [who said]: 'Abd al-Malik ibn 'Umayr narrated to me, from Rifa'ah ibn Shaddad, who said: I used to stand at the head of al-Mukhtar. When I realized his lying, I intended to draw my sword and strike his neck. But I remembered a hadith that 'Amr ibn al-Hamiq narrated to us, [in which] he said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "Whoever grants a man security for his life, then kills him, will be given the banner of treachery on the Day of Resurrection."