Introduction We have already learned above in 7:4 that if most of the community of Israel is impure they observe the first Pesah in impurity. Pesah Sheni is only observed by individuals who could not observe Pesah Rishon due to impurity or distance from the Temple. Our mishnah teaches that only impure Israelites who have become impure through contact with a corpse observe Pesah Rishon while impure; those with impurities that come from their own body do not observe the first Pesah while impure.
The pesah which comes in impurity: zavin and zavot, menstruant women and women after childbirth do not from eat it, yet if they did eat they are exempt from karet. Zavin and zavot are men and women who have had some sort of abnormal genital discharge (see 8:5). The impurity of the menstruant is mentioned in Leviticus 15:19 ff. and that of the woman after childbirth is Leviticus 12:1 ff. People with these types of impurity are not supposed to eat the pesah on Pesah Rishon, even if the community is impure and is eating the Pesah “in impurity”. However, if they do eat the pesah they are not liable for karet as would be the case had they eaten the pesah when the community was pure (see Leviticus 7:20). They are exempt because other people who are eating it are impure.
Rabbi Eliezer exempts [them] even [of the karet normally incurred] for entering the sanctuary. Rabbi Eliezer goes even further. Normally an impure person who intentionally enters the Temple is liable for karet. This is derived from Numbers 5:2 which specifically mentions both the zav and the one defiled by a corpse. From this juxtaposition Rabbi Eliezer learns that the zav and others in a similar category (i.e. the source of impurity is their own body) are liable for entering the Temple only when one defiled by a corpse is liable for entering the Temple. When the pesah is offered by an impure community a person defiled by a corpse is obviously allowed into the Temple. Hence, when this occurs the zav is exempt from entering the Temple as well, even though he doesn’t eat the pesah.