Leviticus 14:3

3And the priest shall go forth. This is the examination, which was more fully treated of in the last chapter, without which it was not lawful to receive him who had been once rejected. The priest’s command, which is mentioned immediately afterwards, I refer to the Levites, some one of whom probably accompanied the priest to prepare the sacrifice, that thus the priests might only discharge the principal duty. The sum of the rite respecting the two birds tends to this, that 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 former was not let go until it had been first dipped in the blood and the water; and thus the matter of sprinkling was prepared for the man’s purification. The sevenfold repetition was intended to impress more deeply on men’s memories a continual meditation on God’s grace; for we know that by this number perfection is often expressed in Scripture. With the same object, he 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. Meantime, on the seventh day he shaved his beard, and his eyebrows, and all the hair of his head; he washed himself and his garments, and then proceeded to the sacrifice. So difficult is it to accustom men to a serious acknowledgment of the two points, to hold their vice in detestation, and worthily to estimate the grace of God whereby they are delivered.