It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "Destruction is for the Arabs because of an evil that has drawn near. Knowledge will decrease and turmoil (harj) will increase." I asked, "O Messenger of Allah! What is meant by harj?" The Noble Prophet (peace and blessings be upon him) said, "Killing."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10926