Exodus 29:4

And Aaron and his sons thou shalt bring unto the door of the
tabernacle of the congregation
That is, order and direct them to come thither; for it cannot be thought he was to carry them in his arms or on his shoulders, or have them thither by force, whether they would or not; but he was to declare to them that it was the will of the Lord they should appear there:

and shalt wash them with water;
out of the laver after mentioned, which stood between the door of the tabernacle of the congregation and the altar: the Targum of Jonathan says, this washing was performed in forty seahs of living or spring water, which was sufficient for the immersion of the whole body, which it is highly probable was the case; and so Jarchi interprets it of the dipping of the whole body, and which seems to have been necessary, upon their entrance on their office, to denote their complete purity and holiness, though afterwards, when they entered on service, they only washed their hands and feet, see ( Exodus 30:18-21 ) to which our Lord seems to allude, ( John 13:10 ) this washing shows what purity and holiness were necessary to the priests of the Lord, and that they ought to be clean that bear the vessels of his house, or minister in his sanctuary, and which were in Christ in their full perfection; and such an high priest became us, who is holy, harmless, and undefiled, and so could offer himself without spot, and was a fit person to take away sin by sacrifice, and to be an advocate for his people: this may also point at his baptism, which he submitted to before he entered on his office in a public manner, and which was performed by immersion; and in this way ought all his priests, his saints, to be washed, as well as with the washing of regeneration, and with the blood of Christ; and which is necessary to their officiating as priests, or drawing nigh to God, and requisite to their communion with God and Christ.