Closes the chapter and the quarrels run.
Quick answer
The liar does not merely damage the person he lies about, he resents them for it. The second line adds flattery to the same charge.
Read both lines
The first line is the harder half and it says something genuinely unpleasant about human nature: the tongue hates those it has crushed. The order is the point. He does not lie because he hates them; he hates them because he lied about them, and the resentment follows the injury rather than causing it. Anyone who has been on the wrong end of this recognizes it immediately, and it is the reason apology is so rare in these situations.
The second line brings the chapter's other weapon back. Flattery and lying were linked at 26:23 through 26:25 as the same craft, and both close here on the word ruin, which is what the chapter has been describing since verse 17.
Related: Proverbs 26:24 · Proverbs 26:18–19 · Proverbs 29:5 · Proverbs 12:19
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.