⚑ The chapter's hardest verse, and the one most easily turned into God arranging pain to improve people. The Hebrew of the first line is genuinely ambiguous, and the context is a courtroom.
Quick answer
The verse belongs to the chapter's run about royal justice, and it observes that real consequences reach a person where argument does not. Its subject is a magistrate, not God.
Read both lines
Two things establish the setting before any interpretation starts. The first is the neighbourhood: verse 26 has a king sifting the wicked and driving a threshing wheel over them, verse 28 has mercy and truth holding up his throne, and this verse closes that run. The subject is a court, not a household and not God's dealings with His children. The second is that the phrase in the second line, inner depths, is the same "rooms of the belly" that verse 27 used of a person's interior. So the observation is that a consequence which actually costs something penetrates to the place a warning does not, which is a plain claim about how people are and not a recommendation of cruelty.
Why translations differ
The first line is one of the more contested in the chapter. The received text preserves two readings of the key word, one a verb (blows scour away evil) and one a noun (blows are a scouring for evil), and the NKJV follows the verbal sense. The syntax also leaves the second line without a verb of its own, which is why the NKJV supplies "as do." This expression is debated, and what cannot responsibly be built on it is any doctrine about how God treats people, because the sentence is not clear enough to carry one and is not about Him in the first place.
What it does not mean
This verse does not say God sends pain to purify anyone, and it must never be used to explain someone's suffering to them. The catalog's standing position holds here without exception: suffering is not God's plan, His reason, or His lesson, and no proverb about a magistrate's sentence establishes otherwise. Two specific misuses need naming. It is not a defense of beating a child, or anyone else; the chapter's own subject is judicial punishment of the wicked, and the book's formation verses carry their own explicit limit at 19:18. And it is not a comfort to offer the grieving, the ill, or the abused. Anyone holding this verse over a person in pain has moved it out of a courtroom and into a place it was never written to go. What the proverb observes is that consequence teaches where words fail. That is all it observes, and it is enough.
Related: Proverbs 20:26 · Proverbs 20:27 · Proverbs 19:18 · Proverbs 13:23
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.