Musnad Ahmad 31:313

Abu al-Walid narrated to us, Shu'bah narrated to us, Khulayd ibn Ja'far narrated to us, from Abu Nadrah, from Abu Sa'id al-Khudri, from the Prophet, peace and blessings of Allah be upon him, who said: "For every treacherous person there is a banner on the Day of Resurrection, by which he is known at his posterior."