Psalm 40:6-8

6Sacrifice and offering You did not desire;
My ears You have opened.
Burnt offering and sin offering You did not require.
7Then I said, “Behold, I come;
In the scroll of the book it is written of me.
8I delight to do Your will, O my God,
And Your law is within my heart.”
-Psalm 40:6-8

As I read this text I think of when Saul was rejected as King over Israel in 1 Samuel 15. Saul was in conquest where he went and destroyed the Amalekites as the Lord had instructed. However, as the Lord had commanded He instructed that all their possessions be destroyed too. Saul and the people of Israel took from their possessions and instead offered them as a sacrifice to the Lord. Many would take this idea and think that it doesn't sound bad. Why not offer this to the Lord? Yet Saul was rebuked for this.

22 So Samuel said:
“Has the Lord as great delight in burnt offerings and sacrifices,
As in obeying the voice of the Lord?
Behold, to obey is better than sacrifice,
And to heed than the fat of rams.
23For rebellion is as the sin of witchcraft,
And stubbornness is as iniquity and idolatry.
Because you have rejected the word of the Lord,
He also has rejected you from being king.”
-1 Samuel 15:22-23

The Lord had instructed for it to be destroyed. Instead Israel turned against the Lord, taking a portion and sacrificing from that instead of walking in obedience to what the Lord had commanded. It is not so simple to say that we will offer everything in our lives to the Lord if we are not walking in obedience. For whatever the Lord may call you to, obey Him in it. The Lord's desire for your life is not that you would simply bring sacrifice but that you would obey.