It [is] an old leprosy in the skin of his flesh
An inveterate one, of long standing and continuance, an obstinate one, not to be cured by medicine; as this sort of leprosy was, and therefore the person was sent not to a physician, but to the priest: the leprosy of sin is an old disease, brought by man into the world with him, and continues with him from his youth upwards, and nothing but the grace of God and blood of Christ can remove it:
and the priest shall pronounce him unclean, and shall not shut him up;
there being no doubt at all of it being a leprosy, and of his uncleanness, and therefore no need to shut him up for further examination, but to turn him out of the camp till his purification was over:
for he [is] unclean;
in a ceremonial sense, and was obliged to the law for cleansing, such as after given.