Proverbs 19:18

Parents are here cautioned against a foolish indulgence of their children that are untoward and viciously inclined, and that discover such an ill temper of mind as is not likely to be cured but by severity. 1. Do not say that it is all in good time to correct them; no, as soon as ever there appears a corrupt disposition in them check it immediately, before it gets head, and takes root, and is hardened into a habit: Chasten thy son while there is hope, for perhaps, if he be let alone awhile, he will be past hope, and a much greater chastening will not do that which now a less would effect. It is easiest plucking up weeds as soon as they spring up, and the bullock that is designed for the yoke should be betimes accustomed to it. 2. Do not say that it is a pity to correct them, and that, because they cry and beg to be forgiven, you cannot find in your heart to do it. If the point can be gained without correction, well and good; but if you find, as it often proves, that your forgiving them once, upon a dissembled repentance and promise of amendment, does but embolden them to offend again, especially if it be a thing that is in itself sinful (as lying, swearing, ribaldry, stealing, or the like), in such a case put on resolution, and let not thy soul spare for his crying.

— Matthew Henry's Concise Commentary (public domain)

(Compare Pro 13:24; Pro 23:13). let not . . . spare--literally, "do not lift up thy soul" (Psa 24:4; Psa 25:1), that is, do not desire to his death; a caution to passionate parents against angry chastisement.

— Jamieson-Fausset-Brown Commentary (public domain)