Musnad Ahmad 908:23

Rawh narrated to us, Abu Yunus al-Qushayri narrated to us, from Simak ibn Harb, from Abdullah ibn Khabbab ibn al-Aratt, my father Khabbab ibn al-Aratt narrated to me, he said: 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. Whoever believes their lies, he shall not come to the Basin (al-Hawd) to meet me."