Anger is one of the most difficult things to control. It is easy for some and very difficult for others. Paul gives the Ephesians (4:26, 27) some instructions concerning controlling their anger.
Paul says they can be angry, but they cannot do something in response to being angry that will be considered a sin. They are to “not let the sun go down on your anger.” They are not to “give the devil an opportunity” when they are angry.