Musnad Ahmad 357:1

Hajjaj narrated to us, he said: Shu'bah narrated to us, from Abu 'Imran, he said: I said to Jundub: "I have pledged allegiance to these people," meaning Ibn al-Zubayr, "and they want me to go out with them to al-Sham." He said: "Refrain." I said: "They refuse." He said: "Ransom yourself with your wealth." I said: "They refuse unless I strike with them with the sword." Jundub said: "So-and-so narrated to me that the Messenger of Allah (ﷺ) said: 'The slain will come with his killer on the Day of Resurrection, and he will say: "O Lord, ask this one why he killed me."'" Shu'bah said: "I think he said: 'And He will say: "For what did you kill him?" He will say: "I killed him for the kingdom of so-and-so."'" He said: Then Jundub said: "So beware of it."