What will be the Din if the Metzora calls the Kohen for a Baheres and when the Kohen arrives, it has turned into a Se'eis?
Sifra: The word "Vehinei" 1 implies that that is precisely what the current Pasuk is referring to and it goes on to obligate the Kohen to examine it for what it is now and to ignore what it was at the time that he was called.
Refer to 13:4:1.1:1.
What are the implications of the (otherwise superfluous) word "ve'Hi Hafchah Se'ar Lavan"?
Sifri #1: With reference to the previous D'rashah, 1 it implies it is the current appearance that turned the hairs white, and not the initial appearance.
Sifri #2: With reference to the previous D'rashah, 2 it implies that it must be the entire Nega (comprising a k'e'Geris) that turns the two hairs white, and not the initial Nega - even one of them.
Seeing as two hairs are a Siman Tum'ah, why does the Torah mention them here together with the Michyah?
Ramban: To teach us (not that two white hairs together with a Michyah are a Siman Tum'ah, but) that two hairs are a Siman Tum'ah and so is a Michyah. 1
See Sifsei Chachamim and Torah Temimah citing the Sifra and note 56.
Seeing as two white hairs are a Siman Tum?ah and so is a Michyah, why does the Torah write them together ? as if both of them are required?
Sifra: To teach us that the minimum size Nega is that of a Michyah plus two white hairs ? which is synonymous with a ki?Geris. 1
See Torah Temimah, note 57.
Having taught us the Din of two white hairs regarding Baheres, why does the Torah repeat it by Se'eis?
Ramban #1: To teach us that they are a Siman Tum'ah in both cases.
Ramban #2 (citing the Sifra): To learn from it that the Michyah must be sufficiently large to contain two hairs. 1
See Torah Temimah, note 51. This is equivalent to the size of a lentil.
What is the definition of the "Michyas Basar Chai" that the Metzora sees in the Se'eis?
Rashi: It is a piece of healthy flesh 1 - without two white hairs - that renders him Tamei, 2 just like two white hairs - irrespective of whether it appears in a Se'eis or in any of the other four appearances of Tzara'as. 3
Sifra: And not a boil or a Bohak (the skin of a Tahor plague). See also Torah Temimah, note 52.
Sifsei Chachamim: We learn this from the (otherwise superfluus) word "Nega Tzara'as". Refer also to 13:10:151:1 & 2.
See Sifsei Chachamim.
What are the implications of "Michyas Basar Chai ba'Se'eis"?
Sifra: It implies that the Michyah must be in the middle of the Se'eis and not at the edge. 1
See Torah Temimah, note 53.
Why does the Torah repeat the word "ba'Se'eis"?
Sifra: To teach us that the Michyah must be in the middle of the Se'eis itself and not in the middle of a boil (or a burn) or a Bohak that happens to be inside the Se'eis.
QUESTIONS ON RASHI
Rashi writes that healthy flesh in the Nega without two white hairs is a Siman Tum'ah. What is the source for this?
Ramban: Pasuk 3 stated that two white hairs by themselves are a Siman Tum'ah in a Baheres (and the same applies to a Se'eis). If so, when the Torah mentions here "Se'or Lavan" and "Michyas Basar Chai" it cannot mean that both are reqrured, but that either of them is a Siman Tun'ah.
Hadar Zekenim and Da'as Zekenim (both in Pasuk 11 and both citing the Sifra): "[Tzara'as Noshenes] Hi" in Pasuk 11 teaches us that a Michyah is Metamei even if it preceded the Baheres.
Refer to 13:10:3:1**.