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.

For Aaron and his sons shall (k) wash their hands and their feet thereat:
(k) Signifying that he that comes to God must be washed from all sin and corruption.

For Aaron and his sons shall wash their hands and their feet thereat. Not in it, but at it; the laver had mouths or spouts, as Ben Melech says, from whence the water flowed when the priests washed their hands and feet at it; and so Bartenora says (z) they did not wash out of the laver, but from water flowing out of it; it is said "out of it", not in it; it seems at first there were but two of these spouts; for it is said (a) Ben Katin made twelve spouts or cocks, which had but two before; so that twelve priests could wash their hands and feet at one time, and which they could do at once, presently, by putting the right hand on the top of the right foot, and the left hand upon the left foot, as both Jarchi and Ben Melech relate: and now the hands being the instruments of action, and the feet of walking, this shows that the actions of good men, the priests of the Lord, and their walk and conversation, are not without sin, and that these need washing in the laver of Christ's blood, to which there must be daily application, see Zac 13:1. Our Lord seems to have reference to this ceremony, John 13:10 the Egyptian priests washed twice every day in cold water, and twice every night (b).
(z) In Misn. Zebachim, c. 2. sect. 1. (a) Misn. Yoma. c. 3. sect. 10. (b) Herodot. Euterpe, sive, l. 2. c. 37.