Why does the Torah write "Emor" and then "v'Amarta"?
Ramban (citing Ibn Ezra) 2 and Seforno: "Emor" refers to the previous Parshah with regard to delving into the Parshiyos there and teaching the people the laws of Tum'ah and Taharah, and to distinguish between the Tahor and Tamei species of animals and birds. 3 Whereas "v'Amarta" pertains to the current Parshah, which places upon the Kohanim additional obligations with regard to Tum'as Mes and desecrating their offspring, in keeping with their higher level of Kedushah.
Ramban, Moshav Zekenim: The Pasuk means that Hashem spoke to Moshe saying. 4
Moshav Zekenim: Some derive this from the change. Everywhere else it says Bnei Aharon, and here it says "ha'Kohanim Bnei Aharon." The Ri asked why we need a verse. Surely we may not be Metamei them, lest they become used to this (and will do so when they mature), This is why Chachamim did not enact Kidush on Yom Kipur, and we will give to a minor to drink! One can distinguish (here there is no concern lest he become used to this, for Tum'as Mes does not occur regularly. - PF)
The Ramban himself states that this explanation is incorrect.
Ramban, Moshav Zekenim: It is as if it had written "Daber el Bnei Yisrael" - like we find in Tehilim, 5:2 and in Mishlei, 22:21 - which the Torah writes when it wishes to emphasize an issue, either due to its severity or because it is something that is constantly transgressed (See R. Chavel's footnotes and Ramban, who elaborates further).
Why does it write both "ha'Kohanim" and "Bnei Aharon"?
Rashi: It writes "Kohanim" to preclude Chalalim from the prohibition, and "Bnei Aharon" to include Ba'alei-Mumin.
Ramban: Whenever the Torah is speaking about the duties of the Kohanim in the Beis-ha'Mikdash, it refers to "Aharon u'Banav", 1 whereas here, where it is speaking about the Kohanim themselves, even when they are not performing in the Beis-ha'Mikdash, it refers to them as Kohanim. 2
See for example , 3:5, 3:8.
Ramban: 'Kohanim of Hashem and servants of our G-d. (Throughout the Parshiyos of Korbanos, the Torah refers to them as "ha'Kohen", "ha'Kohanim" and "Bnei Aharon ha'Kohanim" (See for example , 1:5, 1:9, and 6:22)! Perhaps the Ramban means that only here it says "ha'Kohanim Bnei Aharon" - PF.)
What are the implications of "Bnei Aharon"?
Rashi: To preclude the daughters of Kohanim from the prohibition.
What are the implications of "b'Amav"?
Rashi: To preclude a Mes Mitzvah who is not among the people 1 from the prohibition.
Ramban #1: It means simply that a Kohen is not permitted to render himself Tamei for a Mes of his people.
Ramban #2: With reference to Pasuk 4 2 , it means that 'a master among the people' may not render himself Tamei for a Mes.
Rashbam: It means that someone from the tribe of the Kohanim 3 is not permitted to render himself Tamei Mes.
Seforno: It means that a Kohen may not render himself Tamei for a Mes who is not a relative.
Da'as Zekenim, Hadar Zekenim: He may not become Tamei even for his Am (Kohanim), i.e. relatives (other than the seven close relatives), and all the more so for strangers.
Why does "Emor El ha'Kohanim" follow the previous Parshah (Ov and Yid'oni)?
Hadar Zekenim: Moshe [prophetically] saw Sha'ul's death, and asked why the first king must die this way. Hashem answered, because he told [Do'eg to kill] the Kohanim [of Nov], and he used a Ba'alas Ov to conjure [up Shmuel].
Moshav Zekenim citing R. Yehudah ha'Chasid: Sha'ul asked why he must die unlike other king must die unlike other kings. Hashem said, it is due to killing Kohanei Nov, and using an Ov. Sha'ul asked for pardon. Hashem said, I pardon you for the Ov, but you must "Emor El ha'Kohanim" (ask them to forgive you), and you cannot, for they are dead.
Moshav Zekenim #1: Above (20:25) it discusses dividing between Tahor and Tamei. Tell the Kohanim to sanctify themselves, and separate Aharon to be Kodesh Kodoshim.
Moshav Zekenim #2: Tell Kohanim, who tell Yisrael the future (via the Urim v'Tumim 1 ) and rule for them, to distance from Tum'as Mes, lest people say that they ask Ov and Yid'oni.
R. Chaim Paltiel: Most of the Nevi'im were Kohanim. When others see their relatives telling the future, they might be envious and ask an Ov, so also they will know the future.
Only the Kohen Gadol does so! Perhaps we are concerned lest people say that that he asked Ov and Yid'oni when he was a Kohen Hedyot.
Why is a Kohen Hedyot taught before a Kohen Gadol?
Moshav Zekenim, citing R. Eliezer of Garmaiza: A Kohen Hedyot becomes Tamei for relatives, so he is taught first, near Tum'ah taught above. A Kohen Gadol does not become Tamei even for relatives.
Why are Kohanim forbidden to become Tamei Mes?
Moshav Zekenim: It is lest they be Metamei the Mikdash, for they enter the Mikdash.
What do we learn from "Nefesh"?
QUESTIONS ON RASHI
Rashi writes that "Bnei Aharon" includes Ba'alei-Mumim. It says "ha'Kohanim Bnei Aharon" regarding Korbanos, and a Ba'al Mum is excluded!
Riva: "Kol Ish Asher Bo Mum Lo Yikrav" disqualifies a Ba'al Mum for Avodah. However, it needed to say Bnei Aharon to exclude Bnos Aharon.
Rashi writes that "Bnei Aharon" includes Ba'alei-Mumim. Toras Kohanim expounds that just like Aharon is Kosher, also Bnei Aharon implies without a Mum!
Mizrachi (1:5): Perhaps we really expound from "ha'Kohanim" (to include a Ba'al Mum).
Rashi writes that adults are warned about the children. What does this mean?
Ramban #1: The warning also occurs in connection with Dam and Sheratzim. It extends to all the Isurim in the Torah and is confined to actually assisting the child to sin, but one need not stop him if he sins by himself. 1
Moshav Zekenim #1: Elsewhere, one need not stop him a minor who sins by himself. Tum'ah is different. This is why it does not say about Tum'ah like it says elsewhere 'if a minor is eating Neveilah, Beis Din need not separate him.' Regarding Sheratzim and blood, we read "Lo Tochlum" like "Lo Ta'achilum"; this forbids only feeding him. Here, the inclusion includes every case; even if the minor wants to be Metamei himself, we must stop him.
Ramban #2, Moshav Zekenim #2: The extra warnings teach that also the minors are commanded.
Rashi writes that "Bnei Aharon" excludes Bnos Aharon. Verses exempt women also from Hakafas ha'Rosh and shaving the beard. Why do we need a verse to obligate women in all other Lavim? All agree that Sheloshah Kesuvim (Lavim from which they are exempt) do not teach to elsewhere!
Rashi (Kidushin 35a DH u'Meshani) holds that Shnei (or Sheloshah) Kesuvim do not teach to elsewhere at all. (Without a source, we would not know that women are obligated in other Lavim.) Moshav Zekenim left this difficult. He holds like Tosfos (24b DH Havah Amina), that Shnei (or Sheloshah) Kesuvim teach that elsewhere, the law is the opposite. (PF)
Rashi writes that "Bnei Aharon" excludes Bnos Aharon. Why are they permitted to become Tamei?
Moshav Zekenim citing Ri: The Avodah is through males, and not through females.
Moshav Zekenim: A female (Chavah) brought death to the world, so it is proper that they become Tamei Mes. This is why "v'Lamadnah Venoseichem Nehi" (Yirmeyah 9:19), for they brought death to the world, which causes wailing, and they go in front of the bier.
Rashi writes that "b'Amav" excludes a Mes Mitzvah, who is not among his nation. Why is this needed? Even a Kohen Gadol and Nazir are Metamei for a Mes Mitzvah! We learn from "l'Aviv ul'Imo
Moshav Zekenim: If not for the verse here, one might have thought that it is optional to be Metamei for a Mes Mitzvah. The verse here teaches that it is obligatory.
Moshav Zekenim (4): Our verse 1 teaches that if a Kohen Hedyot and a Nazir are together and find a Mes Mitzvah, the Kohen is Metamei, and not the Nazir, even though the Kohen's Kedushah is permanent.