Jamieson, Fausset and Brown on Hebrews 10:9

9. Then said he--"At that time (namely, when speaking by David's mouth in the fortieth Psalm) He hath said." The rejection of the legal sacrifices involves, as its concomitant, the voluntary offer of Jesus to make the self-sacrifice with which God is well pleased (for, indeed, it was God's own "will" that He came to do in offering it: so that this sacrifice could not but be well pleasing to God).

I come--"I am come."

taketh away--"sets aside the first," namely, "the legal system of sacrifices" which God wills not.

the second--"the will of God" (He 10:7, 9) that Christ should redeem us by His self-sacrifice.