ויקרא, פרק י״ג, פסוק ל״ב

Evaluating a suspected disease on the head or beard requires careful monitoring after an initial week of quarantine. The goal is to determine whether the affliction has expanded or halted. This crucial inspection takes place exactly on the seventh day after the priest's initial observation [רלב״ג]. It must be conducted during daylight hours. Although a bald patch does not require the priest to distinguish between four specific shades of white—unlike a skin affliction, which might suggest that daylight is unnecessary—the law still strictly mandates a daytime examination [מלבי״ם].

The state of the affliction is outlined by describing what has not happened: the bald patch has not spread, and no yellow hair has appeared in it. The primary approach among commentators is that this negative phrasing establishes the opposite rule. If the patch has indeed spread, or if yellow hair has appeared, the individual is declared impure. While these two conditions are presented together, they function independently. The presence of just one sign—either spreading or yellow hair—is entirely sufficient to establish impurity [מזרחי, שפתי חכמים, רלב״ג, גור אריה]. Describing the affliction as not having spread, rather than simply stating it remained unchanged, is a deliberate choice to highlight this precise legal distinction [משכיל לדוד].

The expansion of the affliction refers specifically to the bald patch. The newly spread area does not need to match the exact color of the original spot; the mere loss of additional hair and the widening of the baldness qualify as spreading [פירושי רד"צ הופמן]. This expansion indicates that the underlying decay and disease are gathering strength within the body [רלב״ג]. At this stage of the examination, prior to shaving the hair surrounding the spot, the priest looks for a general expansion of the baldness. Only later is an inspection made to see if the affliction has spread into the skin itself [שד״ל].

The second sign of impurity is yellow hair, understood as thin hair [רלב״ג] possessing a reddish or golden hue [ברכת אשר]. The condition is defined by the simple presence of yellow hair within the spot, rather than a process of hair changing color. This reveals that yellow hair renders the person impure even if it was already present before the bald patch formed [תורה תמימה, מלבי״ם, אדרת אליהו]. Furthermore, because the requirement for the hair to be thin is sometimes omitted in this context, certain commentators suggest that the hair does not strictly need to be thin to cause impurity [מלבי״ם].

Finally, the priest evaluates the visual depth of the affliction. A spot that appears deeper than the surrounding skin typically signals the imminent growth of thin yellow hair [ביאור יש״ר, פירושי רד"צ הופמן]. However, if the spot does not appear deep, has not spread, and has not grown yellow hair, the individual is not automatically cleared. When the affliction remains completely static and lacks definitive signs of impurity, a second week of quarantine is required to continue monitoring the condition [רלב״ג, ביאור יש״ר].