Mishnà su Levitico 13:14

If a nega broke out completely upon one who was unclean, he becomes clean; If the ends of his limbs reappeared, he becomes unclean until the bright spot is reduced to less than the size of a split bean. [If it broke out completely upon him] when he was clean, he becomes unclean; If the ends of his limbs reappeared, he remains unclean until his bright spot resumes its former size.

A bright spot the size of a split bean in which there was quick flesh the size of a lentil and then it broke out covering a person's entire skin and then the quick flesh disappeared, or if the quick flesh disappeared and then the bright spot broke out covering all his skin, he is clean. If quick flesh arose [subsequently], he is unclean. If white hair grew [subsequently]: Rabbi Joshua rules that he is unclean, But the sages rule that he is clean.