Musnad Ahmad 1234:5

Rawh narrated to us, he said: Abu Yunus al-Qushayri narrated to us, from Simak ibn Harb, from Abdullah ibn Khabbab ibn al-Aratt, who said: My father, Khabbab ibn al-Aratt, narrated to me, saying: We were sitting at the door of the Messenger of Allah (may Allah bless him and grant him peace), waiting for him to come out for the noon prayer, when he came out to us and said: "Listen." We said: We have listened. Then he said: "Listen." We said: We have listened. He said: "There will be rulers over you, so do not assist them in their oppression, and do not believe them in their lies. For whoever assists them in their oppression and believes them in their lies, he shall not come to me at the Basin (al-Hawd)."