The 77th prohibition is that anyone who is tameh is forbidden from entering anywhere in the Temple. In later generations, this corresponds to the entire Temple courtyard, from the Gate of Nikanor and inward, which is the beginning of the Courtyard of the Israelites.

The source of this prohibition is G‑d's statement1 (exalted be He), "[Send them out of the camp] and they shall not defile their camp," i.e., the machaneh Shechinah.

In tractate Makkos2 it is explained, "Regarding a person who enters the Temple when he is tameh, both the punishment and the prohibition are written. The punishment is from the verse,3 '[Any person who touches the corpse of a dead person...] shall receive kares if he defiles G‑d's Temple [by entering it].' The prohibition is derived from the verse, '[Send them out of the camp] and they shall not defile their camp.' "

The Mechilta4 says, "The verse 'Command the Jewish people to send out of the camp' constitutes a positive commandment. What is the source for the prohibition? The verse, 'and they shall not defile their camp.' "

This prohibition is repeated with different wording regarding a woman who has recently given birth, "She shall not enter the Temple."5

The Sifra says, "From the verse6 'You must warn the Jewish people about their impurity, so that it not cause them to die [if they defile the Temple that I have placed among them]' I would think that the same applies both from the inside and the outside," i.e., that if he is tameh, he receives kares even if he touches the Temple from the outside. [The Sifra concludes,] "The Torah therefore says regarding a woman who recently gave birth, 'She shall not enter the Temple.' "

There it is explained that the law regarding a woman who has given birth is identical to that of other individuals who are tameh as far as this law is concerned.7

The Sifra also comments on G‑d's statement8 (exalted be He), "If he does not immerse his clothing and body, then he will bear his guilt" — "What does this mean? For not immersing his body, he is punished with kares; for not immersing his clothing, he is punished by receiving 40 lashes. How do we know that this speaks exclusively about someone who is tameh and either enters the Temple or consumes holy offerings? From the fact that it warns, and then indicates the punishment."

We have already explained that one who intentionally transgresses this prohibition is punished with kares. If done unintentionally, the person must bring an offering of adjustable value, as we explained in P72.

The details of this mitzvah are explained in the beginning of tractate Shavuos, in Horios,9 Kerisus,10 and a number of passages in Zevachim.