David's confession quoted in Romans
David confessed his sin in Psalm 51 after Nathan confronted him. Paul later quoted part of that prayer in Romans 3:4.
What if some did not have faith? Will their lack of faith nullify God’s faithfulness? Certainly not! Let God be true and every man a liar. As it is written: “So that You may be proved right when You speak and victorious when You judge.”
Psalm 51 says David wrote it after Nathan came to him. In verse 4, David says God is right when He speaks and blameless when He judges. Romans 3:4 quotes these words to show that God is always true.