19:25

This proverb contrasts the results of disciplining different kinds of people. It also contrasts the ways that different kinds of people learn. No contrast is intended between the similar phrases “will learn prudence” and “will gain knowledge.”

25a
Strike a mocker, and the simple will beware ;

25b
rebuke the discerning man, and he will gain knowledge.

Notice that the parallelism is not exact. The parallel lines function together to imply several things:

(a) A “mocker” learns nothing, even when he is beaten as punishment.

(b) A “simple” person does not learn if someone simply rebukes him. But he does learn from observing the severe punishment of the mocker.

(c) A “discerning man” learns far more readily than a simple person. He is able to learn from even a verbal rebuke. He does not need to see someone else being punished.

19:25a

Strike: In Hebrew, this verb has a wide range of meaning. It probably refers here to striking or beating with a rod or whip.