⚑ One of the most quoted verses in the book, and one of the easiest to turn into a maintenance system.
Quick answer
Concealment does not work and admission is the way out. The verse is describing what hiding does to a person, not setting terms for God's forgiveness.
Read both lines
The first line's claim is experiential before it is moral. The man covering his own transgressions will not prosper, and the word covers thriving of every kind, so the observation is that concealment costs something continuously. David describes the same thing from inside it: "When I kept silent, my bones grew old through my groaning all the day long... I acknowledged my sin to You, and my iniquity I have not hidden" (Psalm 32:3–5).
The second line pairs two verbs, confesses and forsakes, admission and departure, and the pairing is what keeps the verse from being about words alone. Then mercy, which is not earned by the pair but met by it. Note what the verse does not describe: a transaction, a quantity, or a threshold. A man stops hiding and finds mercy already there.
What it does not mean
This is not a system for maintaining your standing with God, and it is regularly preached as one. Read that way it makes forgiveness conditional on a performance of disclosure, and a believer is left auditing whether they confessed thoroughly enough, which is exactly the machinery the cross ended. The believer's standing was settled once and does not fluctuate with the quality of anyone's confession. What confession does is real and worth having: it ends the concealment that was doing the damage, and the damage here is described as happening to the concealer.
Nor is "will not prosper" a promise of material outcomes in either direction. The book is not saying honest people do well financially; it is saying a life organized around hiding does not go well, which is a different and much more defensible claim.
Related: Psalm 32:3–5 · 1 John 1:8–9 · Proverbs 28:1 · Proverbs 10:9
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.