By St. Nikolai Velimirovich
"Be angry and sin not" (Psalm 4:4).
Be angry with yourself, brethren, and sin no more.
Be angry at your sins of thought and deed, and sin no more.
Be angry with Satan the father of lies (John 8:44), and no longer do his will.
Be angry at sin in the world and the trampling of God's holy Church by godless men, but beware that you do not cure sin by sin.
Be angry with your friends when they sin; but be angry with the intention to correct them, and not to embitter them even more. The anger of a friend toward a friend, and the anger of parents toward their children - and of God toward men - is not a storm that uproots the tree but a wind that strengthens the tree, and rids it of rotten fruit so that the healthy fruit will increase in number and beauty.
But let your anger have measure, so that it may be healing and not poisonous. In order to have this kind of control, keep God before you in your anger. There is no stronger containment for anger than God. All anger that is not in the name of God and God's righteousness is a sin.
Do not become angry for the sake of idleness, but become angry for that at which God is angered. If your will is firmly set in God's law, you will always know when it is necessary to be angry, and how much is needed. This cannot be expressed entirely in words, nor can it even be explained to the uneducated. Anger, in its place, acts as mercy does in its place.
O my brethren, do you see how various powers are placed in our souls, and man, by his free will, can utilize them for life or death?
Anger toward oneself can never be recommended enough. Here is a wonderful example: the more a man learns to be angry with himself, the less he is angry with others. Carried away with anger at his own weaknesses, he either does not see the weaknesses of others, or when he does see them, he judges them kindly.
O Lord God, Thou only righteous One, implant in us the remembrance of the Day of Thy righteous anger, so that we may protect ourselves from spiritual sin. To Thee be glory and praise forever. Amen.