Musnad Ahmad 26:268

Abu al-Nadr narrated to us, al-Ashja‘i narrated to us, from Sufyan, from al-A‘mash, from Abu Wa’il, from ‘Abdullah and Abu Musa al-Ash‘ari, who both said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, before the Hour, there are days in which knowledge will be lifted, ignorance will descend, and *al-harj* will increase." He said: And *al-harj* is killing.