Proverbs 21:21 - Ellicott's Commentary On The Whole Bible

Righteousness and mercy. — He who endeavours to give God and man their due (see above on 10:2), and to shew love to them (Proverbs 3:3), will gain for himself length of days (Proverbs 3:16) power to live more and more uprightly, and present honour from God and man for so doing. In a higher sense he will gain life eternal now and hereafter (John 17:3), righteousness, or the forgiveness of sins (Romans 2:13), and honour (Romans 8:30) at the last day, when he will be acknowledged as a true son of God (Romans 8:19).