Leviticus 13:37

But if the scall be in his sight at a stay,.... If in a few days, or in a short space of time after this, it should appear that the scall is at a full stop, and does not spread any further at all:

and [that] there is black hair grown up therein; which is a sign of health and soundness, and so of purity; yea, if it was green or red, so be it, it was not yellow, according to Jarchi, it was sufficient:

the scall is healed; from whence it appears that it had been a leprous scall, but was now healed, an entire stop being put to the spread of it; and though yellow hairs might have appeared in it, yet, as Gersom observes, two black hairs having grown up in it, it was a clear case that the corruption of the blood had departed, and it had returned to its former state:

he [is] clean, and the priest shall pronounce him clean; he was clean before, and is the reason why he pronounces him so; wherefore it is not the sentence of the priest, but the truth of his case that makes him clean; teaching, as Ainsworth observes, that the truth of a man's estate, discerned by the word and law of God, made the man clean or unclean, and not the sentence of the priest, if it swerved from the law.