We do not examine negaim in the [early] morning, nor in the [late] afternoon, nor inside the house, nor on a cloudy day, because what is dull appears bright. Nor [do we examine negaim] in the middle of the day because what is bright appears dull. When do we examine? During the third, fourth, fifth, seventh, eighth, and ninth hours, these are the words of R’ Meir. R’ Yehudah says: during the fourth, fifth, eighth, and ninth hours.

A Kohen who is blind in one eye or whose vision is weak may not examine negaim, because the Torah states: ‘‘as far as the eyes of the Kohen can see.’’ We do not make new windows in a dark house in order to examine its nega.