Pro 29:9 If a wise man contendeth with a foolish man, whether he rage or laugh, there is no rest.
Pro 29:9 智慧人与愚妄人相争，或怒或笑，总不能使他止息。
I prefer Jamieson, Fausset and Brown Commentary and Albert Barnes' Notes upon this verse:
"whether ... laugh — The fool, whether angry or good-humored, is unsettled; or referring the words to the wise man, the sense is, that all his efforts, severe or gentle, are unavailing to pacify the fool." JFB
"All
modes of teaching - the stern rebuke or the smiling speech - are alike
useless with the “foolish” man; there is “no rest.” The ceaseless
cavilling goes on still." Barnes
If the "rage or laugh" from the verse refers to the fool's
reaction, then it is to say that the wise man should not have done so.
But it is the wise who would rage or laugh, which are the natural
effects towards the impenitent response of the fool, then there is a
lesson for all of us who seek wisdom in order that we control ourselves
in proper use of anger and wise teaching, and not let restless anger or
scornful humor turn us into heartless beings. So that when iniquity
abounds, our love shall endure unto the end.