Musnad Abu Ya'la al-Mawsili 243:14

Sa'id ibn Yahya ibn Sa'id al-Umawi narrated to us, my father narrated to me, Abu Burdah ibn 'Abdullah ibn Abi Burdah narrated to us, from Abu Burdah, from Abu Musa, who said: The Messenger of Allah (ﷺ) said: "Indeed, before the Hour, there will be *al-harj*." We said: "And what is *al-harj*?" He said: "Killing, killing. Until a man kills his neighbor, his cousin, and his father." He (the narrator) said: "And we witnessed the killing of fathers during the time of the Azariqah."