According to the last United Nations survey, there are about 12,000 murders in the USA each year. There were all kinds of circumstances behind those murders, but you can be sure of one thing. ANGER was at the heart of all of them. Jesus went straight to the heart of the matter.
Dallas Willard put it this way, Anger and contempt are the twin scourges of the earth, these bitter emotions form the poisonous brew in which human existence stands suspended. Few people ever get free of them in this life, and for most of us even old age does not bring relief. To cut off the root of anger is to wither the tree of human evil. (Dallas Willard, The Divine Conspiracy p. 151)