Musnad Ahmad 788:231

'Affan narrated to us, he said: Hammad bin Salamah narrated to us, he said: 'Ali bin Zayd informed us, from Hattan bin 'Abdullah ar-Raqashi, from Abu Musa, from the Prophet (peace be upon him), who said: "Indeed, before the Hour, there will be al-harj." They said: "And what is al-harj?" He said: "Killing." They said: "More than what we kill? We kill more than seventy thousand in a single year." He said: "It is not the killing of the polytheists, but rather the killing of some of you by others." They said: "And will we have our intellects on that day?" He said: "The intellects of most of the people of that time will be snatched away, and there will remain for it the dregs of the people; most of them will think that they are upon something, while they are upon nothing." Abu Musa said: "By the One in Whose hand is my soul, I do not find for myself or for you any way out of it, if it reaches me and you, except that we exit it just as we entered it, having shed no blood and taken no wealth."