*Minor differences ignored. Grouped by changes, with first version listed as example.
To "despise" a mother is to cause her the deepest grief, and is therefore not unfitly contrasted with "making a glad father."
A wise son maketh a glad father,.... See Gill on Proverbs 10:1;
but a foolish man despiseth his mother; that bore him and brought him up, and perhaps was too indulgent to him; which aggravates his sin and her sorrow; See Gill on Proverbs 10:1; or causes her to be despised by others, as Jarchi interprets it; such a man's sin, which is great folly, and shows him to be a foolish man, is highly resented by the Lord, and will be severely punished; see Proverbs 30:17. The Targum is,
"a foolish son despises his mother;''
and so the Septuagint, Syriac, and Arabic versions, which makes the antithesis more clear; and the Hebrew text designs one grown up to man's estate.
Those who treat an aged mother or a father with contempt or neglect, show their own folly.
This collection of Solomonic proverbs began, Proverbs 10:1, with a proverb having reference to the observance of the fourth commandment,
(Note: The fifth commandment of the Westminster Shorter Catechism is named as the fourth in Luther's catechism.)
and a second chief section, Proverbs 13:1, began in the same way. Here a proverb of the same kind designates the beginning of a third chief section. That the editor was aware of this is shown by the homogeneity of the proverbs, Proverbs 15:19; Proverbs 12:28, which form the conclusion of the first and second sections. We place together first in this new section, Proverbs 15:20-23, in which (with the exception of Proverbs 15:25) the ישׂמח [maketh glad] of the first (Proverbs 10:1) is continued.
20 A wise son maketh a glad father,
And a fool of a man despiseth his mother.
Line first = Proverbs 10:1. The gen. connection of כּסיל אדם (here and at Proverbs 21:20) is not superlative the most foolish of men, but like פּרא אדם, Genesis 16:12; the latter: a man of the wild ass kind; the former: a man of the fool kind, who is the exemplar of such a sort among men. Piety acting in willing subordination is wisdom, and the contrary exceeding folly.
*More commentary available at chapter level.