(Mishnah): If one steals ha'Kisvah (this will be explained), curses b'Kosem (in the name of idolatry), or has Bi'ah with a Nochris, zealots may kill him [while he is doing the Aveirah].

If a Kohen did Avodah when he was Tamei, the other Kohanim do not take him to Beis Din. Rather, the young Kohanim take him outside of the Azarah and bruise his brain with pieces of wood.

R. Akiva says, if a Zar (non-Kohen) did Avodah in the Mikdash, he is choked;

Chachamim say, [Beis Din does not kill him.] He is Chayav Misah b'Yedei Shamayim (at the hands of Heaven).

(Gemara): Kisvah is a Kli.

(Rav Yehudah): It is a Kli of the Beis ha'Mikdash, like it says "v'Es Kesos ha'Nasech."

Cursing b'Kosem is like these Nafta'ei (a certain nation) curse [in the name of idolatry] to Kanyech (your Maker), Kainech or Kanvach (the latter are corruptions of "Kanyech" - ALEI TAMAR.)

(Tana d'Vei R. Yishmael): One who [is Mechaneh b'Arayos, i.e. explains them euphemistically, i.e. "umi'Zar'acha Lo Siten Leha'avir l'Molech"] is one who marries a Nochris and fathers children. He raises enemies to Hash-m.

It says "va'Yar Pinchas ben Elazar ben Aharon ha'Kohen" - what did he see? He saw the act (Zimri was having Bi'ah with Kozbi) and remembered the Halachah, that one who has Bi'ah with a Nochris, zealots may kill him.

(Beraisa): Chachamim are displeased [with zealots who kill - KORBAN HA'EDAH].

Question: Was Pinchas's act against Chachamim's will?!

Answer (R. Yudah bar Pazi): [Indeed, Chachamim of the generation] wanted to excomuunicate him, had Ru'ach ha'Kodesh not said "v'Haysah Lo ul'Zar'o Acharav Bris Kehunas Olam..." (Then they understood that Hash-m approved.)