He that begetteth a fool doeth it to his sorrow: and the father of a fool hath no joy.

Jamieson-Fausset-Brown Bible Commentary

21. (Compare Pr 23:24). Different words are rendered by "fool," both denoting stupidity and impiety.

Matthew Henry's Concise Commentary

17:19. If we would keep a clear conscience and a quiet mind, we must shun all excitements to anger. And a man who affects a style of living above his means, goes the way to ruin. 20. There is nothing got by ill designs. And many have paid dear for an unbridled tongue. 21. This speaks very plainly what many wise and good men feel very strongly, how grievous it is to have a foolish, wicked child. 22. It is great mercy that God gives us leave to be cheerful, and cause to be cheerful, if by his grace he gives us hearts to be cheerful. 23. The wicked are ready to part with their money, though loved, that they may not suffer for their crimes. 24. The prudent man keeps the word of God continually in view. But the foolish man cannot fix his thoughts, nor pursue any purpose with steadiness. 25. Wicked children despise the authority of their father, and the tenderness of their mother. 26. It is very wrong to find fault for doing what is duty. 27,28. A man may show himself to be a wise man, by the good temper of his mind, and by the good government of his tongue. He is careful when he does speak, to speak to the purpose. God knows his heart, and the folly that is bound there; therefore he cannot be deceived in his judgment as men may be.