레위기 13:32의 미드라쉬

1) (Vayikra 13:32) ("And the Cohein shall see the plague-spot on the seventh day, and, behold, if the nethek has not spread, and there was no yellow hair in it, and the appearance of the nethek is not deeper than the skin") "on the seventh": I might think either by day or at night (before the seventh day); it is, therefore, written "on the day," and not at night.

2) For I might think that the skin of the flesh, which confers tumah through four "appearances," requires daylight, but nethakim, which do not confer tumah through four appearances, do not require daylight; it must, therefore, be written (also in respect to nethakim) "in the daytime," and not at night.

3) R. Yehudah says: Wherever the stipulation of precedence (of nega to hair) must be made, it is made (explicitly, in the verse itself), but nethek, about which it is written (Vayikra 13:32) "and there is no yellow hair in it" (without any explicit stipulation of precedence), (nethek) confers tumah whether or not it precedes (the yellow hair).