Kelim, Chapter One, Mishnah Eight
1) The area within the wall [of Jerusalem] is holier, for it is there that lesser holy things and second tithe may be eaten.
2) The Temple Mount is holier, for zavim, zavot, menstruants and women after childbirth may not enter it.
3) The chel is holier, for neither non-Jews nor one who contracted corpse impurity may enter it.
4) The court of women is holier, for a tevul yom may not enter it, though he is not obligated a hatat for doing so.
5) The court of the Israelites is holier, for a man who has not yet offered his obligatory sacrifices may not enter it, and if he enters he is liable for a hatat.
6) The court of the priests is holier, for Israelites may not enter it except when they are required to do so: for laying on of the hands, slaying or waving.
Section one: Within the walls of Jerusalem is holier than within other walled cities, for within these walls one may eat lesser holy things (kodashim kalim) such as the pesah sacrifice and shelamim sacrifices. One may also eat second tithe inside the walls of Jerusalem.
Section two: Men or women who are zavim or zavot, and menstruants and women after childbirth are not allowed to enter the Temple Mount. This is stated with regard to the woman who gave birth in Leviticus 12:4.
Section three: The chel is a sort of corridor surrounding the Temple’s courtyards. See Middot 2:3. Strictly speaking, its area is not considered part of the Temple. Non-Jews and Jews who contracted corpse impurity are not allowed into this area. This seems to be an extra insurance policy to keep these two categories further away from the Temple itself.
Section four: The Women’s court was the first court into which one would enter upon entering the Temple. See Middot 2:5-6. A person who had gone to the mikveh but who had not yet waited till sundown could not go into this court, meaning he/she cannot enter the Temple. However, if he/she accidently enters this court, he is not liable for a sin-offering, as would be a person who entered the Temple while fully impure.
Section five: After going through the Women’s Court, one would enter the Israelites’ court. Obviously, any impure Israelite cannot enter here. The mishnah adds that a metzora (skin disease) who had been purified but had not yet offered his sacrifices cannot enter this area, and if he does so, he is liable for a hatat.
Section six: The Priests’ Court is basically off limits to the Israelites. However, they may enter in order to perform one of the sacrificial actions that they are either obligated or permitted to perform. These including laying one’s hands on the sacrifice (see Menahot 9:8), slaughtering the sacrifice (Israelites can, but do not have to perform thissee Zevahim 3:1) and waving the sacrifice (see Menahot 5:6-7).