Musnad Ahmad 1018:104

Bahz narrated to us, Hammad ibn Salamah narrated to us, he said: Abu Imran informed us, he said: I said to Jundub, "I pledged allegiance to Ibn al-Zubayr that I would fight the people of al-Sham." He said: "Perhaps you want to say: 'Jundub gave me a legal opinion, and Jundub gave me a legal opinion'?" I said: "I do not intend that, except for my own self." He said: "Redeem yourself with your wealth." I said: "He will not accept it from me." He said: "I was a sturdy youth during the time of the Prophet, may Allah bless him and grant him peace, and so-and-so informed me that the Messenger of Allah, may Allah bless him and grant him peace, said: 'The slain person will come on the Day of Resurrection clinging to the killer, and he will say: "O Lord, ask him why he killed me." He will say: "For the dominion of so-and-so."'" So fear [Allah], and do not be that man.