Charles Ellicott Commentary Exodus 40:12

"And thou shalt bring Aaron and his sons unto the door of the tent of meeting, and shalt wash them with water." — Exodus 40:12 (ASV)

Thou shalt bring Aaron and his sons ... and wash them. —See Note on Exodus 29:4. Ablution, investiture, and anointing had all been previously appointed to be parts of the consecration service (Exodus 29:4–5; Exodus 29:7, and so forth).