4:26

Be wrathful: Paul quotes from Ps 4:4, showing that it is not wrong for Christians to feel anger. Jehovah and Jesus both express anger in response to wickedness and injustice, but their anger is always governed by righteousness and perfect judgment. (Eze 38:18, 19; see study note on Mr 3:5.) Christians too may feel righteous anger, but Paul says do not sin. Christians do not allow anger to lead to uncontrolled outbursts, abusive speech, or violence. (Eph 4:31) Ps 4:4 advises God’s servants to express their concerns about the cause of their anger in private prayer to Jehovah.

do not let the sun set while you are still angry: To the Jews, sunset marked the end of one day and the beginning of another. So Paul here warns against letting anger fester from one day to the next. In fact, Jesus warned his disciples not to continue to be wrathful with someone. (Mt 5:22) Prolonged anger may lead to bitterness, grudges, and divisions in personal relationships and within the congregation. (Le 19:18; Ps 36:4; Ga 5:19-21) Paul offers practical counsel to help Christians resolve problems quickly, the same day if possible.​—Ro 12:17-21; Eph 4:2, 3.