15 The rod and reproof give wisdom: but a child left to himself bringeth his mother to shame.
Parents, in educating their children, must consider,
1. The benefit of due correction. They must not only tell their children what is good and evil, but they must chide them, and correct them too, if need be, when they either neglect that which is good or do that which is evil. If a reproof will serve without the rod, it is well, but the rod must never be used without a rational and grave reproof; and then, though it may be a present uneasiness both to the father and to the child, yet it will give wisdom. Vexatio dat intellectum–Vexation sharpens the intellect. The child will take warning, and so will get wisdom.
2. The mischief of undue indulgence: A child that is not restrained or reproved, but is left to himself, as Adonijah was, to follow his own inclinations, may do well if he will, but, if he take to ill courses, nobody will hinder him; it is a thousand to one but he proves a disgrace to his family, and brings his mother, who fondled him and humoured him in his licentiousness, to shame, to poverty, to reproach, and perhaps will himself be abusive to her and give her ill language.
– Matthew Henry Commentary