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 God.
do not let the sunset 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. (Leviticus 19:18; Psalms 36:4; Gal. 5:19-21) Paul offers practical counsel to help Christians resolve problems quickly, the same day if possible.. Romans 12:17-21; Eph 4:2, 3.
Romans 12:17-21 NET
17 Do not repay anyone evil for evil; consider what is good before all
people.[a] 18 If possible, so far as it depends on you, live peaceably
with all people.[b] 19 Do not avenge yourselves, dear friends, but
give place to God’s wrath,[c] for it is written, “Vengeance is
mine, I will repay,”[d] says the Lord. 20 Rather, if your enemy
is hungry, feed him; if he is thirsty, give him a drink; for in doing
this you will be heaping burning coals on his head.[e] 21 Do not be
overcome by evil, but overcome evil with good.
Ephesians 4:2-3 NET
2 with all humility and gentleness,[a] with patience, putting up
with[b] one another in love, 3 making every effort to keep the unity
of the Spirit in the bond of peace.