Throughout the Old Testament, God instituted rituals and rhythms for His people. These ceremonial laws taught Israel who God was and who they were to be as they lived life before Him. In this way, the ceremonial laws, including the sacrificial system of the Old Testament, were not intended to be an end in themselves but rather as means that would point to deeper truths (Rom. 10:4).
David picks up on this thought in Psalm 40 when he writes:
In sacrifice and offering you have not delighted, but you have given me an open ear. Burnt offering and sin offering you have not required. Then I said, “Behold, I have come; in the scroll of the book it is written of me: I delight to do your will, O my God; your law is within my heart.” (vv. 6–8)
It appears at the outset that David may be attempting to undo something God has done, disregarding the need for perpetual sacrifices for sin. We know he isn’t doing that by appealing to other portions of Scripture. Instead, David is pointing us to a deeper truth. David is showing that what God desires more than and in addition to external obedience is an internal love for God shown by a delight in the law of God.
The Christian might respond to this passage with a “Yes, less ritual, more gospel affection, more heart!” But we should be careful. The same David who made such a bold claim about his heart devotion also had a cold enough heart toward God to commit murderous adultery (2 Sam. 11–12) and to take an ill-advised census (2 Sam. 24). David could not live before God without perpetual sacrifices for sin and the need to repent for a wayward heart (Ps. 51). The Christian cannot afford to trust in external or internal obedience for right standing before God.
There is a solution other than tossing our hands in the air. The author of Hebrews employs Psalm 40 to show that Jesus succeeded where David failed.
When [Jesus] said above, “You have neither desired nor taken pleasure in sacrifices and offerings and burnt offerings and sin offerings” (these are offered according to the law), then he added, “Behold, I have come to do your will.” He does away with the first in order to establish the second. And by that will we have been sanctified through the offering of the body of Jesus Christ once for all. (Heb. 10:8–10)
Jesus is the ultimate voice behind Psalm 40. Jesus fulfilled the sacrificial system by offering Himself once for all as a sacrifice to satisfy God’s wrath against sin. Jesus provided His active obedience, His perfect life of love toward God, on the sinner’s behalf. In Christ, therefore, the Christian has a solution to impotent external works of obedience and anemic internal affections toward God. The Christian has to look to Christ in faith not only as an example but also as a Savior.