'Office' in the Bible

“Now bring your brother Aaron near, and his sons with him from among the sons of Israel, so that he may serve as priest to Me—Aaron, Nadab and Abihu, Eleazar and Ithamar, Aaron’s sons.

These are the garments which they shall make: a breastpiece and an ephod [for the breastpiece] and a robe and a tunic of checkered work, a turban, and a sash. They shall make sacred garments for Aaron your brother and his sons, so that he may serve as a priest to Me.

And you shall wrap them with sashes, Aaron and his sons, and put the [ornamental] caps on them; and the priest’s office shall be theirs by a perpetual statute. So you shall ordain Aaron and his sons.

I will sanctify the Tent of Meeting and the altar [of burnt offering]; also I will sanctify Aaron and his sons to serve as priests to Me.