| Matthew Henry's Concise Commentary 18:19. Great care must be taken to prevent quarrels among relations and those under obligations to each other. Wisdom and grace make it easy to forgive; but corruption makes it difficult. 20. The belly is here put for the heart, as elsewhere; and what that is filled with, our satisfaction will be accordingly, and our inward peace. 21. Many a one has caused his own death, or the death of others, by a false or injurious tongue. 22. A good wife is a great blessing to a man, and it is a token of Divine favour. 23. Poverty tells men they must not order or demand. And at the throne of God's grace we are all poor, and must use entreaties. 24. Christ Jesus never will forsake those who trust in and love him. May we be such friends to others, for our Master's sake. Having loved his own, which were in the world, he loved them unto the end; and we are his friends if we do whatever he commands us, Joh 15:14.
Pulpit CommentaryVerse 20. - With the first clause, comp, Proverbs 12:14, and with the second, Proverbs 13:2. A man's belly; i.e. himself, his mind and body, equivalent to shall he be filled, or satisfied, in the second clause. A man must accept the consequences of his words, good or evil. The next verse explains this.
Gill's Exposition of the Entire BibleA man's belly shall be satisfied with the fruit of his mouth,.... With his own words and discourses, when they are prudent, pious, and savoury; when they are with grace, and minister it; they are satisfying to himself, to his own mind and conscience, and to his family; to all within his house, which is, as it were, his belly; but, if otherwise, it will not be profitable nor satisfying to either; and therefore, if a man would keep conscience easy, and be useful to others, he ought to take care what he says; see Proverbs 12:14; and with the increase of his lips shall he be filled; the same thing as before, expressed in different words, alluding to the sowing, of seed in the earth, and the increase of it; as a man sows he reaps, and enjoys the fruits of his labour; according to what a man sows with his lips, such is his harvest he is afterwards a partaker of.
Jamieson-Fausset-Brown Bible Commentary20. (Compare Pr 12:14; 13:2). Men's words are the fruit, or, increase of his lips, and when good, benefit them. satisfied with—(Compare Pr 1:31; 14:14).
Proverbs 18:20 Parallel Commentaries Proverbs 18:20 NIV
Proverbs 18:20 NLT
Proverbs 18:20 ESV
Proverbs 18:20 NASB
Proverbs 18:20 KJV Bible Hub: Online Parallel Bible | 
