The fourth of five places Proverbs warns against standing surety, and the NKJV footnotes all three key terms.
Quick answer
Guaranteeing someone else's debt is filed here as a failure of judgment. The book has said this four times and will say it once more.
Read both lines
The NKJV footnotes are dense: "devoid of understanding" is literally lacks heart, "shakes hands" is literally strikes the hands, and "surety" is guaranty or collateral. All three appear in the same cluster at 6:1–5, 11:15, 20:16, and 22:26–27. Placing this two verses after 17:16, which used the identical lacks heart idiom, is the chapter's own comment: the man with money and no appetite for wisdom and the man pledging against a debt he does not control have the same thing missing. The distinction chapter 6 drew still holds. Generosity gives what it has; surety promises what it may not have.
Related: Proverbs 6:1–5 · Proverbs 11:15 · Proverbs 22:26–27 · Proverbs 17:16
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.