For by one offering he has perfected forever those who are being sanctified.
For--The sacrifice being "for ever" in its efficacy (Heb 10:12) needs no renewal. them that are sanctified--rather as Greek, "them that are being sanctified." The sanctification (consecration to God) of the elect (Pe1 1:2) believers is perfect in Christ once for all (see on Heb 10:10). (Contrast the law, Heb 7:19; Heb 9:9; Heb 10:1). The development of that sanctification is progressive.
Here the apostle raises up and exalts the Lord Jesus Christ, as high as he had laid the Levitical priesthood low. He recommends Christ to them as the true high priest, the true atoning sacrifice, the antitype of all the rest: and this he illustrates, I. From the purpose and promise of God concerning Christ, which are frequently recorded in the volume of the book of God, Heb 10:7.
Commenting on Hebrews 10:7-18
For by one offering,.... The same as before; himself, body and soul; this is a reason why he is set down, and will continue so for ever, and why he expects his enemies to be made his footstool; because by one sacrifice for sin, which he has once offered, he hath perfected for ever them that are sanctified; that is, who are sanctified by God...