A.T. Robertson Commentary Hebrews 10:9

"then hath he said, Lo, I am come to do thy will. He taketh away the first, that he may establish the second." — Hebrews 10:9 (ASV)

The which (αιτινες). "Which very things" (θυσια).

Then hath he said (τοτε ειρηκεν). That is Christ. Perfect active indicative with which compare τοτε ειπον (second aorist active) in verse 7 which is quoted again.

He taketh away the first (αναιρε το πρωτον). Present active indicative of αναιρεω, to take up, to abolish, of a man to kill (Matthew 2:16). By "the first" (το πρωτον) he means the system of animal sacrifices in verse 8.

That he may establish the second (ινα το δευτερον στηση). Purpose clause with ινα and the first aorist active (transitive) subjunctive of ιστημ, to place. By "the second" (το δευτερον) he means doing God's will as shown in verse 9 (following verse 8). This is the author's exegesis of the Psalm.