How do we know that Christ speaks in Psalm 40?

The interpretation of Psalm 40 as the voice of Christ is substantiated by its citation in Hebrews 10:5-7, where the writer explicitly attributes these words to Jesus. The nature of Christ's statements in this psalm, particularly His references to waiting on the Lord and His willing obedience to God's will, highlights His unique role as the mediator and savior. The psalm also describes the empathy of Christ as He identifies with human suffering, bearing our iniquities. Thus, every word serves to illustrate His perfect fulfillment of the law and His redemptive mission.