Charles Ellicott Commentary Leviticus 13:31

"And if the priest look on the plague of the scall, and, behold, the appearance thereof be not deeper than the skin, and there be no black hair in it, then the priest shall shut up [him that hath] the plague of the scall seven days:" — Leviticus 13:31 (ASV)

It be not in sight deeper than the skin.—Better, its appearance is not deeper than the other skin, if the first symptom which manifests itself in the depression of the affected spot is absent.

And that there is no black hair in it.—Better, but there is no black hair in it; that is, the healthy black colour of the hair is absent, which is a suspicious sign. The phrase “there is no black hair in it” is another way of saying “there is yellow hair in it.”

The presence of yellow hair on the first inspection, however, though suspicious, did not by itself necessarily indicate leprosy. This is because the hair sometimes turned yellow temporarily in the case of an ordinary ulcer and resumed its natural black colour when the patient returned to usual health.

Hence, the absence of black hair was simply a suspicious symptom, which required the attention of the priest. For this reason, the patient had to be put in quarantine for seven days.

The alteration of the word “black” into “yellow,” which has been adopted by those commentators who follow the Septuagint, is therefore unnecessary. Indeed, if this reading is adopted, both the unfavourable symptoms mentioned in Leviticus 13:30, which indicate leprosy—namely, (1) the depression of the affected spot, and (2) the discolouring of the hair—would be absent. There would then be no reason for quarantine, as the priest, in the absence of these criteria, would have to pronounce the man clean .