What the psalmist believes their LORD desires is a life that is lived according to the covenant rather than sacrifice and offering.
Like the prophets (see for example 1 Samuel 15: 22; Isaiah 1: 12-17; Hosea 6:6 and Amos 5: 21-24), here the psalmist recounts that the LORD desires more than merely right worship. The God of the psalms is not swayed by lavish sacrifices or offerings or worship. No sacrifice meets what God truly wants for God’s people. Instead it is a life lived in trust, praise and obedience that is desired by God. While worship, sacrifice and offering are all a part of this life they are not sufficient.
~Psalm 40 Experienced Faithfulness and the Hope of Deliverance by
“Sign of the Rose“