Musannaf Ibn Abi Shayba 37:170

Narrated to us Abd al-A’la, from Ma’mar, from al-Zuhri, from Sa’id, from Abu Hurayrah, from the Prophet (peace and blessings of Allah be upon him), who said: "Time will draw near, knowledge will decrease, stinginess will be cast [into hearts], tribulations will appear, and al-harj will increase." They said, "O Messenger of Allah, what is al-harj?" He said, "Killing."