Musnad Ahmad 30:2272

Qutaybah ibn Sa'id narrated to us, Ya'qub narrated to us, from Suhayl, from his father, from Abu Hurayrah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The Hour will not be established until wealth becomes abundant and overflows, to the extent that a man will go out with the Zakat of his wealth, and he will not find anyone to accept it from him. And until the land of the Arabs returns to being meadows and rivers, and until *al-harj* becomes abundant." They said: "And what is *al-harj*, O Messenger of Allah?" He said: "Killing, killing."