It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: The Day of Judgment will not be established until the land of Arabia becomes filled with rivers and streams, and until a rider travels between Iraq and Mecca and has no fear except of losing his way, and until killing (harj) becomes widespread. The companions (may Allah be pleased with them) asked: O Messenger of Allah! What is meant by harj? He replied: Killing.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 8833