This seems to be a restatement of the first verse in this chapter.
(Proverbs 15:1 NAS77) A gentle answer turns away wrath, But a harsh word stirs up anger.
Then you put this together with how agape love is described in I Corinthians 13,
(1 Corinthians 13:4-5 NAS77) Love is patient, love is kind, and is not jealous; love does not brag and is not arrogant, does not act unbecomingly; it does not seek its own, is not provoked, does not take into account a wrong suffered,and the fruit of the Spirit in Galatians 5,
(Galatians 5:22-23 NAS77) But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law.This gives you a picture of how Christian relationships should be conducted. The way we relate to non-believers is important. Even harder, this deals with how we relate to other believers. The hardest is getting along with family members.
As Jesus becomes the center of our lives He becomes the Lord of our mouth as much as the Lord of our heart. We no longer retaliate with sharp words, or we shouldn’t. We slow down, let agape do its work and either stifle ourselves totally or speaks gently.
So? Righteousness makes a difference in our need to get the last word.