משלי י:יג פירוש: רש״י

Wisdom is found in the lips of the understanding When a person reproves an understanding individual, he replies to him, “I have sinned,” e.g. David, who said to Nathan, “I have sinned” (11 Sam. 12:13).

but a rod is for the body of one devoid of sense But one who is devoid of sense does not listen until he is smitten, like Pharaoh.