Midrash su Levitico 14:48

8) Whence is it derived that if it remained the same in this (the first week) and in this (the second week), he removes, scrapes, and plasters, and is given an additional week? From its being written (instead of) "and if the Cohein comes," (Vayikra 13:44), "and if the Cohein come, shall come" — two comings. Of what is this speaking? If of its having spread in the first week, this has already been stated. If of its having spread in the second week, this has already been stated. It must be speaking of his having come at the end of the first week and at the end of the second week, (Vayikra 13:44) "and he shall see, and, behold, the plague-spot has not spread," i.e., it remains the same. What should be done? Can I think that he (simply) leaves and walks away? It is, therefore, written (Vayikra 13:44) "for the plague-spot has been healed." I have cleansed only what has been healed (through an additional removal, scraping, etc. [See Rashi in Chumash]).

(Exod. 2:20:) HE SAID UNTO HIS DAUGHTERS: SO WHERE IS HE? Zipporah (Tsipporah) immediately {went out} [ran] like a bird (tsippor) and brought him. Another interpretation: Why was she called Zipporah (Tsipporah)? Because she cleansed her father's house like the blood of a bird (tsippor).⁵⁴According to Lev. 14:48–55; Neg. 13:1, such a cleansing was needed for a house with a curable plague of leprosy.