משנה על נגעים 2:1

Rabbi Hanina, the vice-chief of priests, says: the colors of negaim are sixteen. Rabbi Dosa ben Harkinas says: the colors of negaim are thirty-six. Akaviah ben Mahalalel says: seventy-two. Rabbi Hanina the vice-chief of priests says: negaim may not be inspected for the first time at the end of Shabbat, since the end of that week will fall on Shabbat; Nor on a Monday, since the end of the second week will fall on Shabbat; Nor on a Tuesday, in the case of houses, since the end of the third week will fall on Shabbat. Rabbi Akiva says: they may be inspected at all times, and if the time for the second inspection falls on Shabbat it is postponed to after Shabbat; and this procedure leads sometimes to a leniency and sometimes to a stringency.