These verses are parenthetic. They interrupt the narrative of what Moses did “on the first day of the first month,” informing us of the use whereto the laver was applied subsequently. (Comp. Exodus 30:19-21.)
Related Commentaries of Exodus 40:31
Exodus 40:31-32
31 And Moses and Aaron and his sons washed their hands and their feet thereat:
32 When they went into the tent of the congregation, and when they came near unto the altar, they washed; as the LORD commanded Moses.