Albert Barnes Commentary Exodus 30:17-21

"And Jehovah spake unto Moses, saying, Thou shalt also make a laver of brass, and the base thereof of brass, whereat to wash. And thou shalt put it between the tent of meeting and the altar, and thou shalt put water therein. And Aaron and his sons shall wash their hands and their feet thereat: when they go into the tent of meeting, they shall wash with water, that they die not; or when they come near to the altar to minister, to burn an offering made by fire unto Jehovah. So they shall wash their hands and their feet, that they die not: and it shall be a statute for ever to them, even to him and to his seed throughout their generations." — Exodus 30:17-21 (ASV)

(Exodus 38:8) The bronze for the “Laver of brass” and its foot was supplied from the bronze mirrors of the women who voluntarily gave up these articles of luxury. Bronze mirrors were much used by the ancient Egyptians. No hint is given as to the form of the laver. The brazen sea and the ten lavers that served the same purpose in the temple of Solomon were elaborately worked in artistic designs and are minutely described (1 Kings 7:23–29).

(Exodus 30:19) Wash their hands and their feet – On certain solemn occasions he was required to bathe his whole person (Exodus 29:4; Leviticus 16:4). The laver must also have furnished the water for washing those parts of the victims that needed cleansing (Leviticus 1:9).

(Exodus 30:20) That they die not – See (Exodus 28:35) note.