Albert Barnes Commentary Hebrews 10:8

"Saying above, Sacrifices and offerings and whole burnt offerings and [sacrifices] for sin thou wouldest not, neither hadst pleasure therein (the which are offered according to the law)," — Hebrews 10:8 (ASV)

Above, when he said. That is, the Messiah. The word "above" refers here to the former part of the quotation. This means that, having stated in the former part of the quotation that God did not require sacrifices, in the latter part, he says that he came to do the will of God in their place.

Sacrifice and offering and burnt offerings, etc. These words are not all used in the Psalm from which the apostle quotes, but the idea is that the specification there included all kinds of offerings. The apostle dwells upon it because it was important to show that the same remark applied to all the sacrifices which could be offered by man. When the Redeemer made the observation about the ineffectiveness of sacrifices, he meant that none of them would be sufficient to take away sin.