Psalm 40:9 portrays the psalmist publicly proclaiming righteousness in the great congregation and refusing to keep God's saving truth to himself. David bears witness openly to what God has done.

Matthew 4:17 summarizes the beginning of Jesus' public preaching: "Repent, for the kingdom of heaven is at hand." Matthew does not cite Psalm 40:9 as a prediction, so the relationship is thematic. Jesus fulfills the role of God's supreme herald by publicly announcing God's righteousness, kingdom, and saving purpose. What David does as a worshiper testifying before Israel becomes part of a larger biblical pattern of proclamation that reaches its fullest authority in Christ's teaching.