Musnad Ahmad 1034:62

Sulayman narrated to us, Isma'il informed us, 'Amr narrated to me, from 'Abdullah ibn 'Abd al-Rahman al-Ash-hali, from Hudhayfah ibn al-Yaman, that the Prophet, peace and blessings of Allah be upon him, said: "The Hour will not be established until you kill your leader, and strike one another with your swords, and the worst of you inherit your worldly life."