John Calvin Commentary Leviticus 14:3

"and the priest shall go forth out of the camp; and the priest shall look; and, behold, if the plague of leprosy be healed in the leper," — Leviticus 14:3 (ASV)

And the priest shall go forth. This is the examination, which was more fully discussed in the last chapter, without which it was not lawful to receive the one who had previously been rejected. The priest’s command, mentioned immediately afterward, I refer to the Levites, one of whom probably accompanied the priest to prepare the sacrifice, so that the priests might only discharge the principal duty.

The essence of the rite concerning the two birds is this: the cleansing from leprosy was a kind of resurrection. Two birds were placed before their eyes; the liberty of one was purchased by the blood of the other, because the first was not released until it had first been dipped in the blood and the water. In this way, the means for sprinkling was prepared for the man’s purification.

The sevenfold repetition was intended to impress more deeply on their memories a continual meditation on God’s grace, for we know that by this number perfection is often expressed in Scripture.

For the same purpose, the one who had been cured shaved his hair and washed in water. Yet he did not return home on the first day, but on the eighth. Meanwhile, on the seventh day, he shaved his beard, his eyebrows, and all the hair of his head; he washed himself and his garments, and then proceeded to the sacrifice.

It is so difficult to accustom people to a serious acknowledgment of these two points: to hold their vice in detestation, and to rightly value the grace of God by which they are delivered.