"If you, O LORD, kept a record of sins, O Lord, who could stand? But with you there is forgiveness; therefore you are feared."
-- Psalm 130:3-4 (NIV)
Growing up in a Missouri-Synod Lutheran home, I learned that John 3:16 was called the Gospel in a Nutshell, meaning that it was the basic overall Gospel message condensed into one verse. And while I don't believe in over-simplification, it's nice to have one go-to verse to rely on when you don't have time to read through half the New Testament in one sitting. I reckon John's ability to pack so much into 26 words is part of what made this the most well-known verse in Christendom.
But the above verses, while not quite as detailed and not nearly as well-known, could be called the Law and Gospel in a Nutshell. Speaking directly to the LORD, the Psalmist proclaims, "If you, O LORD, kept a record of sins, O Lord, who could stand?" That wraps up the Law pretty well, I'd say. We are sinners. There's no way around it. And if God kept a record of the sins we commit, none of us would be able to stand under His Judgment. We are helpless and miserable sinners.... Law.
But the Psalmist continues, "But with you there is forgiveness; therefore you are feared." We don't have to live in our sin. There is forgiveness... with God. Not with anyone else. And therefore, He is feared. God doesn't have to show us forgiveness, mercy, and boundless grace... But He does.... Gospel.
Again, while not quite as detailed as the commonly-known Gospel in a Nutshell, the Law and Gospel in a Nutshell tells the sinner what he/she needs to know. If God judged us according to our deeds, we'd be doomed... But He chooses to forgive us instead, and look not on our sins, but on the perfect sacrifice of Christ crucified for us.... All that packed into 2 small verses. Well done, Psalmist. Walther would be proud.