Psalm 40:6–8,

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.”

For many of us, Psalm 40:6–8 is a riddle, wrapped in a mystery, inside an enigma — as Winston Churchill once said of Russia.

Verses 1–10 are David’s song of thanks to God for rescuing him from dire straights. Verses 6–8 then raise the issue of what should David do in response to God’s life-saving rescue. Slaughter another sheep? Sacrifice a bull or goat? Is that really an apt response to God pulling him up from the very pit of destruction (verse 2)? Thanks for saving my life, God. Here’s a goat. It doesn’t work.

A Gap to Be Filled

What David is sensing is that there’s a gap between the magnitude of the divine deliverance and the paucity of mere animal sacrifice as the human response. David has put his finger on a tension, and it is a dissonance that is growing throughout the Old Testament (in places like 1 Samuel 15:22 and Psalm 51:16 and more). Sacrificing another animal isn’t sufficient. At best it’s provisional. It is plainly not ultimate. It screams for fulfillment, for resolution, for satisfaction. It’s tangibly prophetic. And here in Psalm 40, David is recognizing that it can only be self-sacrificial obedience — the giving of one’s all — that will even begin to fill such a gap.

David’s Unique Role

The superscription is important: David, the psalmist, is also Israel’s king, and the mediator between God and the people. And the old covenant mediator has the gall to say to God, in the presence of his people, “In sacrifice and offering you have not delighted.” “What you really want is not the sacrifices of the old covenant, but me — all of me.”

And as mediator, he’s aware of his unique role, which he mentions in verse 7 when he says it is written of him in the scroll of the book (likely a reference to Deuteronomy 17:14–20).

Ready to Offer Himself

In his great zeal, inspired by his deep gratitude, David is ready to step forward to bridge the gap between the magnitude of God’s deliverance and the inadequacy of animal sacrifice. He is ready to offer his whole self, rather than bulls and goats. And so he says, “Behold, I have come; in the scroll of the book it is written of me; I desire to do your will, O my God; you law is within my heart.” David himself is the offering.

But it is enough? Can David really be the one who steps forward? Broadly speaking, what he has to say in verses 6–8 is true. The covenant of animal sacrifice is unavoidably temporal and passing away. There is a greater sacrifice required and inevitably coming, and the role of the mediator is to represent God to the people and the people to God. Yes, what David says is true, but if we press it hard enough, we see that he is speaking beyond himself in a kind of sanctified hyperbole — or better, a prophetic pointer. Verses 6–8 are about David, yes, but there’s a true and better David that embodies verses 6–8 more than David ever could.

The Better David

When the better David says, “Behold, I have come,” he doesn’t mean that a mere human king has come onto the scene of history, but that in an utterly unique way, the divine has come down from heaven and taken on humanity. And when the better David says, “in the scroll of the book it is written of me,” he means not only Deuteronomy 17:14–20, or various obscure parts of the Pentateuch relating to kingship, but he means, as in Luke 24, “all the Scriptures” (24:27) — “the Law of Moses and the Prophets and the Psalms” (24:44). And when the better David says, “I desire to do you will, O my God” — or “Not as I will, but as you will” (Matthew 26:39) — he does so in Gethsemane on the eve of his crucifixion, dying as the mediator of a new covenant for the people he represents.

Perhaps the most profound difference between David and this better David, named Jesus, is that David’s body can’t cash the check his zeal is ready to write. David can’t bridge the gap between God’s mercy and man’s need that his burst of gratitude has him fired up for. But Jesus can. Jesus does live a perfect life. He does not have the iniquities that David confesses in verse 12. Jesus is not only able to offer himself, but able to be fully accepted by God as the perfect sacrifice.

Jesus’ Saving Obedience

And so David, in his zeal to obey God, models for us faintly the kind of zeal to obey God that not only led Jesus to empty himself of divine prerogative, but humble “himself by becoming obedient to the point of death, even death on a cross” (Philippians 2:7–8), and in doing so, become the founder and perfecter of our faith (Hebrews 12:2).