Mischna zu Wajikra 13:58

[A nega] that remained unchanged during the first week must be washed and isolated. One that remains unchanged during the second week must be burned. One that spread during the first or the second week must be burned. If it becomes dimmer in the beginning: Rabbi Ishmael says: it should be washed and isolated. But the sages say: he is not required [to do so]. If the nega became dimmer during the first week it must be washed and isolated. If it became dimmer during the second week it must be torn out, and that which is torn out must be burnt, and it is necessary for a patch to be put on. Rabbi Nehemiah says: a patch is not necessary.