Musnad Ahmad 788:13

Muhammad ibn Ubayd narrated to us, al-A’mash narrated to us, from Shaqiq, who said: Abdullah and Abu Musa were sitting, and they were discussing a hadith. Abu Musa said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Before the Hour, there are days in which knowledge will be lifted, ignorance will descend, and al-harj will increase." And al-harj is killing.