Exodus 30:18

Thou shalt make a laver of brass The laver, or font, was a large vessel, that would contain a good quantity of water. The foot of brass, it is supposed, was so contrived as to receive the water, which was let out of the laver by spouts or cocks. They then had a laver for the priests only to wash in; but to us now there is a fountain opened for Judah and Jerusalem, Zechariah 13:1, an inexhaustible fountain of living water, so that it is our own fault if we remain in our pollution. Aaron and his sons were to wash their hands and feet at this laver every time they went in to minister. For this purpose, clean water was put into the laver fresh every day. Though they washed themselves ever so clean at their own houses, that would not serve, they must wash at the laver. This was designed to teach them purity in all their ministrations, and to possess them with a reverence of God's holiness, and a dread of the pollutions of sin. They must not only wash and be made clean when they were first consecrated, but they must wash and be kept clean whenever they went in to minister. He only shall stand in God's holy place that hath clean hands and a pure heart, Psalms 24:3. And it was to teach us, who are daily to attend upon God, daily to renew our repentance for sin, and our believing application of the blood of Christ to our souls for remission.