Matthew Poole and continuators on Hebrews 10:9

9 Then said he, Lo, I come to do thy will, O God. He taketh away the first, that he may establish the second.

In this Verse the Apostle collects the Psalmists Assertion of God the Father's accepting his Sacrifice, the offering whereof was so exactly agreeable to his Will, when he was displeased with the legal ones, and this revealed to David when he was punctually using them according to the Law.

God therefore abolished all the legal Sacrifices, which he commanded to be used as Types of the better Sacrifice he had provided, because of their Insufficiency and Weakness as to expiate Sin, or pacifie Conscience, that he might establish that Sacrifice of the Body of Christ for abolishing Sin, and bringing in everlasting Righteousness, which was effectual, and an actual Obedience agreeable to his Will and Command, Phil. 2.7, 8. This being thus proved, he concludes from it, v. 10.