New Defender's Study Bible Notes
10:12 sat down. The high priests in Israel could never be seated while ministering (Hebrews 10:11), for their work was never finished. They could only enter the most holy place once each year, but Christ sat down at God’s right hand, after offering one sacrifice for sins forever.
10:13 footstool. This refers to the promise of Psalm 110:1, which also speaks of Christ as “of the order of Melchizedec.”