Musnad Ahmad 770:1

'Affan narrated to us, Abu 'Awanah narrated to us, Ziyad ibn 'Alaqah narrated to us, he said: I heard Jarir ibn 'Abdullah stand to deliver a sermon on the day Al-Mughirah ibn Shu'bah died. He said: "You must fear Allah, the Almighty and Majestic, and maintain dignity and tranquility until an amir (leader) comes to you, for he will come to you now." Then he said: "Seek pardon for your amir, for he used to love pardon." And he said: "To proceed: I came to the Messenger of Allah, peace and blessings of Allah be upon him, and said: 'I pledge allegiance to you upon Islam.' The Messenger of Allah, peace and blessings of Allah be upon him, said—and he stipulated to me—: 'And [to offer] sincere advice to every Muslim.' So I pledged allegiance to him upon this. By the Lord of this mosque, I am indeed a sincere advisor to you all." Then he sought forgiveness and descended.