Adam Clarke on Hebrews 10:11

Every priest standeth - The office of the Jewish priest is here compared with the office of our High Priest. The Jewish priest stands daily at the altar, like a servant ministering, repeating the same sacrifices; our High Priest offered himself once for all, and sat down at the right hand of God, as the only-begotten Son and Heir of all things, Heb 10:12. This continual offering argued the imperfection of the sacrifices. Our Lord's once offering, proves his was complete.