God become flesh in order to fulfill the sacrificial system. He came to provide a true sacrifice, one that would completely atone for human sin. Jesus, the God-man, came in order to show what it means to have a “open ear” to the commandments of God. Jesus obeyed perfectly - His merits completely righteous and His righteousness a provision for sinners to stand before their holy God so that “in him we might become the righteousness of God” (2 Cor. 5:21).
Psalm 40 records this conversation for our benefit. In it, we see the sacrificial system as an example of God’s grand plan to make what was designed to point to a Rescuer, intentionally declared obsolete because it would be replaced by something far better and completely permanent - God in flesh, Jesus, with the Word of God both in His ear and on His heart!