Musnad Ahmad 27:1259

'Abd al-Samad ibn 'Abd al-Warith narrated to us, Sakhr narrated to us, from Nafi', that Ibn 'Umar gathered his sons when the people of Medina rose up with Ibn al-Zubayr and renounced Yazid ibn Mu'awiyah. He said: "We have pledged allegiance to this man upon the pledge of Allah and His Messenger, and I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: 'A treacherous person will have a banner set up for him on the Day of Resurrection, and it will be said: This is the treachery of so-and-so.' And indeed, among the greatest of treacheries—except for associating partners with Allah the Exalted—is that a man pledges allegiance to a man upon the pledge of Allah and His Messenger, then he breaks his pledge." So let none of you renounce Yazid, and let none of you exceed the limits in this matter, for it would be a cause of severance between me and you.