Ephesians 4:26

Be ye angry, and sin not—So the Septuagint, Psalms 4:4. Should circumstances arise to call for anger on your part, let it be as Christ's "anger" (Mark 3:5), without sin. Our natural feelings are not wrong when directed to their legitimate object, and when not exceeding due bounds. As in the future literal, so in the present spiritual, resurrection, no essential constituent is annihilated, but all that is a perversion of the original design is removed. Thus indignation at dishonor done to God, and wrong to man, is justifiable anger. Passion is sinful (derived from "passio," suffering: implying that amidst seeming energy, a man is really passive, the slave of his anger, instead of ruling it).

let not the sun go down upon your wrath—"wrath" is absolutely forbidden; "anger" not so, though, like poison sometimes used as medicine, it is to be used with extreme caution. The sense is not, Your anger shall not be imputed to you if you put it away before nightfall; but "let no wrath (that is, as the Greek, personal 'irritation' or 'exasperation') mingle with your 'anger,' even though, the latter be righteous, [TRENCH, Greek Synonyms of the New Testament]. "Put it away before sunset" (when the Jewish day began), is proverbial for put it away at once before another day begin (Deuteronomy 24:15); also before you part with your brother for the night, perhaps never in this world to meet again. So JONA, "Let not night and anger against anyone sleep with you, but go and conciliate the other party, though he have been the first to commit the offense." Let not your "anger" at another's wickedness verge into hatred, or contempt, or revenge [VATABLUS].