In the 32nd Psalm, David had no idea what he was saying when he wrote, "Happy the man to whom the Lord by no means shall be reckoning depravity." He had to have read it after he wrote it and said, "What the hell is THAT?" because there was no teaching in Israel, no thought that even entered the Jewish mind concerning sin not even being reckoned. The Israelite tabernacle system, instituted by God, DEALT with sin. Without the reckoning of sin, there would be no need for a propitiatory shelter.

God put that sentence on ice for 1,000 years. If you don't care for that analogy, you might want to think of mothballs. Paul finds that sentence 1,000 years later (thaws the ice, brings it up from the mothballs) and uses it as a springboard (and a witness) in his teaching on justification by faith.