Whoso keepeth the law is a wise son,.... That observes the law of God; for, though he cannot perfectly keep it, yet he delights in it after the inward man; and with his spirit serves it, from a principle of love, in faith, and with a view to the glory of God, without mercenary and sinister ends. Such a man enjoys peace, and has a reward "in" though not "for" keeping the commands of it; so that it is his wisdom to observe it; and he may be truly called a wise man, Deuteronomy 4:6; Or that observes the law or commandments of his parents, which they enjoin him; see Proverbs 6:20; and particularly the law of God, which requires honour and obedience to be given to parents, and which turns to the account of children; it is well with them, and their days are prolonged on earth, and therefore they are wise that keep it, Ephesians 6:1; and such a wise son makes a glad father, as the contrary brings shame to him, as in the next clause;
but he that is a companion of riotous men shameth his father: that keeps company with gluttons, and indulges his sensual appetite with them; that "feeds" (d) such persons and himself, as some render the word; that gives up himself to an epicurean life: he brings himself at last to disgrace and poverty, and so causes shame to his father; who will be charged with neglecting his education, and indulging him in such a luxurious way of living; see Proverbs 10:5.
(d) "qui pascit", V. L. Pagninus, Piscator, Gejerus, Schultens; "pascitar", Michaelis; "pascens", Montanus.

Companions of riotous men not only grieve their parents, but shame them.

(Compare Proverbs 17:25).
riotous men--or, "gluttons" (Proverbs 23:20-21).

7 He who keepeth instruction is a wise son;
But he that is a companion of profligates bringeth his father into shame.
We have translated תורה at Proverbs 28:4 by "law;" here it includes the father's instruction regarding the right way of life. נוצר תּורה, according to the nearest lying syntax, has to be taken as pred. זוללים are such as squander their means and destroy their health, vid., under Proverbs 23:20. רעה signifies, as frequently from the idea of (cf. Proverbs 29:3) pasturing, or properly of tending, to take care of, and to have fellowship with. יכלים shall put to shame denotes both that he himself does disgrace to him, and that he brings disgrace to him on the part of others.