Why does the Torah insert the word "ba'Yom ha'Shevi'i"?
Sifra: To teach the Kohen that he must examine the Nega by day. 1
Even in the day, he may only examine the Nega when it is completely light, but not early in the morning, at dusk or when it is cloudy. See Torah Temimah citing the Sifra , and note 34.
What are the connotations of the word "be'Einav"?
Rashi, Targum Onkelos and Targum Yonasan: It means that the Nega retained its appearance and its size. 1
Ramban (citing the Sifra) and Da'as Zekenim: It means that the appearance of the Nega did not change in the eyes of the Kohen. 2
As in Beha'aloscha Bamidbar ,11:7 and in Yechezkel, 1:22 (Ramban). The Da'as Zekenim asks that, in that case, the Torah should have said "Omeid be'Einav"?, and the Hadar Zekenim asks that it should have said "be'Einav Amad", in which case, "be'Einav" could refer only to the Nega; But "Omeid be'Einav" is ambiguous. - PF)
See Ramban.
Why does the Torah write "Shiv'as Yamim Sheinis" (and not 'Shiv'as Yamim Acherim')?
Sifra: To teach us that the seventh day pertains to both the first week and the second week - so that the second week terminates at the end of the thirteenth day. 1
See Torah Temimah, note 35.
What if the Nega spreads after the first week?
