Prov 15:21

“Note, 1. It is the character of a wicked man that he takes pleasure in sin; he has an appetite to the bait, and swallows it greedily, and has no dread of the hook, nor feels from it when he has swallowed it: Folly is joy to him; the folly of others is so, and his own much more. He sins, not only without regret, but with delight, not only repents not of it, but makes his boast of it. This is a certain sign of one that is graceless. 2. It is the character of a wise and good man that he makes conscience of his duty. A fool lives at large, walks at all adventures, by no rule, acts with no sincerity or steadiness; but a man of understanding, the eyes of whose understanding are enlightened by the Spirit (and those that have not a good understanding have no understanding), walks uprightly, lives a sober, orderly, regular life, and studies in every thing to conform himself to the will of God; and this is a constant pleasure and joy to him. But what foolishness remains in him, or proceeds from him at any time, is a grief to him, and he is ashamed of it. By these characters we may try ourselves.”

“Folly is joy to him that is destitute of wisdom,.... Or "that wants a heart" (q), a wise and understanding one; by "folly" is meant sin, for all sin is folly; and that is very pleasing and joyous to a wicked he chooses it and delights in it; instead of being ashamed of it, and sorry for it, he glories in it, and makes his boast of it; and not only takes pleasure in committing it himself, but also in those that do it; see Pro 10:23; but a man of understanding walketh uprightly; he who has his understanding enlightened by the Spirit of God; who has an understanding given him by the Son of God; who has a spiritual and experimental understanding of the Gospel, and the truths of it: he walks according to the rule of the divine word; he walks as he has Christ for an example, and by faith on him; and after the spirit, and not after the flesh: or "directs himself in walking" (r), his goings, as the Vulgate Latin version, according to the above rule, example, and guidance, by the assistance of the spirit and grace of God; otherwise it is not in man that walketh of himself to direct his steps, Jer 10:23. (q) "carenti corde", Montanus; "ei qui deficitur", Schultens. (r) "diriget seipsum ambulando", Montanus; "diriget ambulare, vel ad ambulandum", Vatablus; "diriget viam suam ad ambulandum", Mercerus, Gejerus.”