Musnad Ahmad 31:437

'Abd al-Samad narrated to us, al-Mustamir narrated to us, Abu Nadra narrated to us, from Abu Sa'id, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "For every treacherous person there is a banner on the Day of Resurrection, raised for him according to the extent of his treachery. Beware, there is no treachery greater than the treachery of a general leader."