Pesachim 9:4-5

Pesachim 9:4

If the Passover offering was brought in a state of ritual impurity (which was permitted when the majority of the people were unclean), it may not be eaten by a zav or a zavah (a man or woman who experienced various types of emissions), a menstruant woman or a woman who has just given birth (because this only exempts those suffering from corpse uncleanliness, not other forms of ritual impurity). If such people do eat from it, they are not subject to kareis (excision). Rabbi Eliezer even exempts these people from kareis if they should happen to enter the Temple.

Pesachim 9:5

The differences between the original Passover offering, which was brought in Egypt, and subsequent Passover offerings are: the original Passover offering was purchased on 10 Nisan, had to be sprinkled with hyssop on the doorposts and lintel, and was eaten in haste on one night. The Passover holiday of subsequent generations lasts a full week.