Part of the fool run. Restates verse 1 with a mechanical image.
Quick answer
Honoring a fool is tying the stone into the sling. You have defeated the instrument by the very act of loading it.
Read both lines
A sling works by release, so a stone bound in it is not merely useless but self-defeating, and there is a second edge: a bound stone whirled at speed is dangerous to the man holding it. Both senses fit. Honor given to a fool does not travel where it was aimed, and it may hurt the person who conferred it.
The verse restates verse 1 and adds the mechanism. There the objection was seasonal, honor in the wrong weather; here it is mechanical, honor prevented from doing the thing honor does, which is to point a community toward someone worth imitating.
Related: Proverbs 26:1 · Proverbs 19:10 · Proverbs 25:27
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.