“Every priest stands day after day... He sat down”
Day after day every priest stands to minister and to offer again and again the same sacrifices, which can never take away sins. But when this Priest had offered for all time one sacrifice for sins, He sat down at the right hand of God. (Hebrews 10:11–12 BSB)
What it sounds like today
A posture detail without obvious weight.
The cultural key
There was no chair in the sanctuary. Scan the tabernacle furniture list: lampstand, table, altars, ark, and not one seat, because the priests' work was never finished; they ministered standing, daily, the same offerings forever. Against that standing liturgy, one verb detonates: he sat down, the enthronement of Psalm 110:1 ('Sit at my right hand,' the verse Jesus claimed at his trial). Sitting is what you do when the work is complete.
Recovered meaning
The whole argument of Hebrews in body language: standing priests mean unfinished business; a seated priest is a contradiction in terms unless the sacrifice actually worked, once, for all time. The empty space where the sanctuary's chair should have been is filled at God's right hand.