Why does it say "Ki Rabas ha'Kahal"?
'Rashi' (16): This is why the Leviyim did Shechitah, and not the owners, for many (Malbim - most) of Yisrael did not become Tehorim.
Redak: It means many of the congregation. Rabas is a noun, like "Rabas Tzeraruni mi'Ne'urai."
If they are not Tehorim, they may not eat Pesach, and they do not fulfill the Mitzvah!
Redak, Malbim: This was Pesach ha'Ba b'Tum'ah, so Temei'im could eat it. They could not do anything else, e.g. enter the Azarah to offer it, since it was possible via others 1 - Leviyim did Shechitah for them.
Malbim (2) explained that according to R. Shimon, Pesach was not brought b'Tum'ah (refer to 30:2:1:4*). Perhaps they immersed from Tum'ah today, so they are Tevul Yom. They will be totally Tahor at night to eat it, but now they may not enter the Azarah. (PF)
This is like Rav Chisda; Rava holds that Temei'im may offer Pesach ha'Ba b'Tum'ah (Pesachim 79a). (PF)
