Musnad Abu Ya'la al-Mawsili 159:45

Bishr ibn al-Walid narrated to us, Abu Ma'shar al-Madani narrated to us, from Sa'id al-Maqburi and Musa ibn Sa'd, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The Hour will not be established until *al-harj* increases." They said: "And what is *al-harj*, O Messenger of Allah?" He said: "Killing," three times. They said: "Every year we kill a thousand or two thousand of the polytheists." He said: "I do not mean that, but rather you will kill one another." They said: "And we will be alive and doing that?" He said: "Allah will cause the hearts of the people of that time to die, just as He causes their bodies to die."