A Matter of Death and Life

Rashi:"Speak to the kohanim"
...to admonish the adult to be responsible for the minors... "Speak [to the Kohanim and say" [This repeated expression comes] to admonish the adult [Kohanim to be responsible] for the minors [that they must not contaminate themselves].

"the sons of Aaron"
[Had Scripture used just this expression,] I would have thought that even desecrated [kohanim, those born from forbidden unions, as in verse 7, are included in this admonition to separate from uncleanness]. Scripture, therefore, states, "the kohanim" [to teach us that the admonition applies only to non-desecrated kohanim].

"the sons of Aaron"
Even those who have defects are implied.

"the sons of Aaron"
But not the daughters of Aaron [who may become defiled for the dead].

"Let none [of you] defile himself [for a dead person] among his people"
While the dead person is among his people [and therefore has people, non- kohanim, to bury him]. This comes to exclude [from the prohibition a kohen who comes across] a "mait mitzvah", [a dead person for whom no one is in calling distance to attend to his burial and thus it is incumbent on the kohen to attend to him].

Baal HaTurim: "Say… and you shall say"
The first saying prohibits a Kohen from contracting impurity by contact with a corpse. The second saying obligates him to contaminate himself in a manner in case of a 'Meit Mitzvah/a dead person of whom there is a commandment' to bury because no one else is.

"to the kohanim"
The gematria of the phrase is 161, equal to "Ze Lo Chalalim"; this excludes Chalalim -- defiled one's referring to the offspring of a kohanim and a woman forbidden to him.

"V’amarta/and you shall say"
the gematria of this word (647) = that of LeDorot/for all generations.

"not to a [dead] person"
The gematria of the phrase is 491, equal to BeDam Hameit/by the blood of a corpse

Ramban: The reason for mentioning "the priests" is that concerning the offerings he never refers to them by the name "the priests", but here He warns the priests that they should never defile themselves for the dead, even at a time when they don't come into the sanctuary, this being a mark of personal distinction. As ministers of our G‑d, they are to conduct themselves in a manner reflecting honor and greatness, and they should never become defiled. Thus priests who are unfit for priesthood can defile themselves for the dead.

Ohr HaChayim: "Emor"
The word 'Emor/say' implies a compliment, and advantage; the words "to the Kohanim" intend to justify the compliment, because the priests go in and out in the Tabernacle, i.e. G‑d's Presence where they perform service for the King of Kings. What is this compliment? The priests are not to defile themselves though contact with the dead. Seeing that Kohanim are privileged to enter the Tabernacle and to be in G‑d's presence most of the time, their present superior status is mentioned first before the Torah tells us how they came to be priest, through being descendants of Aaron. If the Torah had used regular language, this point would not have come across.

Ohr HaChayim: "el HaKohanim"
The Torah saw fit to repeat "el HaKohanim" by saying "amarta". It is simply that the Torah commands both the priest not to defile himself and anyone else not to defile him. "El HaKohanim" tells the priest not to defile himself, whereas "amarta" tells others not to defile the priest.

Degel Machane Efraim: The greatest defilement is to worship and pray with a coldness and a sense of distance from the prayers one is saying.

Mei HaShilo'ach: Death causes a form of Tumah, a disembodied soul residue which may get in the way of a priest doing his duties, so must be avoided by those ministering to the people. The soul asks: Why is there such a vacuum sucking life energy out of the world. The answer is that neither death nor life are separate entities distinct from each other. Both must be seen as part of a larger whole.

Mezritcher Maggid: The priests are a particularly kind group who devote much of their time to guiding the rest of the people on the right path. However, since this requires them to rebuke the people, they are warned "Let no priest become ritually impure with a person among your people: When you are "among your people" i.e. giving them words of rebuke, be careful that you do not have any ulterior motive, because if you do, you (the priest) will become "ritually impure."

Zohar Emor 88:
"Speak to the priests" — in a whisper. Just as all the services of the priests are done silently, so are all their words whispered. "Speak...and say" once and again to remind them of their sanctity so that they shall not be defiled, for whoever serves in a holy place must be holy in every respect. "There shall none be defiled for the dead," as we explained that a spiritless corpse is unholy and the spirit of defilement dwells upon it. For the spirits of defilement long for the bodies of Yisrael, once the spirit of holiness was emptied from them, and they come to join a vessel of holiness. The priests, who are doubly holy must not be defiled whatsoever, as written, "because the crown of his G‑d is upon his head" (Num. 6:7) and "the anointing oil of his G‑d is upon him". (Lev. 21:12)