There are many occasions when a Christian may be rightly angered by some ugly word or incident and thus be strongly tempted to respond in kind. Our text, however, reminds us that such a reaction for a Christian is sin, and it urges us to get control of our anger before sundown. We are not to let our anger fester until it breaks out in action.
A very similar command was given long ago to Old Testament believers also. "Stand in awe, and sin not: commune with your own heart upon your bed, and be still. Selah" (Psalm 4:4). When angry, it is far better to wait and communicate with God about it in bed than to bring recriminations in the street (or, perhaps, in the home) against the ones who have angered us.
The Lord Jesus Himself is always our example, "Who, when he was reviled, reviled not again; when he suffered, he threatened not; but committed himself to him that judgeth righteously" (1 Peter 2:23).
Anger is often one of the most difficult areas to overcome in the Christian life. As James says, "The tongue can no man tame . . . Therewith bless we God, even the Father; and therewith curse we men, which are made after the similitude of God . . . . My brethren, these things ought not so to be" (James 3:8-10). Nevertheless, what man cannot tame, God can!
"Wherefore, my beloved brethren, let every man be swift to hear, slow to speak, slow to wrath: For the wrath of man worketh not the righteousness of God" (James 1:19-20). "Avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord" (Romans 12:19). Anger may come, but to act in anger is sin. HMM