Musnad Ahmad

Abu Imran, may Allah have mercy on him, says that I said to Jundub that I have pledged allegiance to Sayyiduna Abdullah bin Zubair, may Allah be pleased with him, and these people want me to go with them to Syria. Jundub said, "Do not go." I said, "They do not allow me to do otherwise." He said, "Save yourself by paying a ransom." I said, "They are not willing to accept anything except that I go with them and show my skills with the sword." Upon this, Jundub said, "Such-and-such a man narrated this hadith to me, that the Messenger of Allah, peace and blessings be upon him, said: On the Day of Resurrection, the murdered person will bring his killer before Allah and say, 'O Lord! Ask him why he killed me?' So Allah, the Exalted, will ask him, 'For what reason did you kill him?' He will say, 'Because of the rule of so-and-so.' Therefore, you should beware of this."