Halakhah su Levitico 21:6

That is that He commanded us to honor the seed of Aharon, to adorn and glorify them, and that we should place them on a level of priority and precedence. And even if they decline, we should not listen to them - this is all aggrandizement of God, may He be exalted, since He took them and chose them for His service and to offer His sacrifices. And this is His, may He be exalted and may His name be blessed, saying, "And sanctify him, since he offers the bread of your God" (Leviticus 21:8)." And the explanation appears - "And sanctify him," in every matter of holiness: To start first, to bless first and to take a nice portion. And the language of the Sifrei is, "'And sanctify him' - against his will." This means to say this is a command that we are commanded, and it is not the priest's choice. And likewise did they say, "'They shall be holy to their God' (Leviticus 21:6) - against their will; 'and they shall be holy' - to include those with blemishes." This is so that you not say, "Since this one is not fit to serve the bread of His God, why should we give him the level of priority and honor?" Hence His saying, "and they shall be holy" - all of this honored seed, both unblemished and blemished. And the stipulations required by them, such that it will be fit to treat them with this practice, have already been explained in scattered places in the Gemara - in Chullin, in Shabbat, in Bekhorot and in the other [tractates]. (See Parashat Emor; Mishneh Torah, Vessels of the Sanctuary and Those who Serve Therein 4).

It is from the roots of the commandment [that] since the priests were chosen for the service of God, blessed be He - as the verse stated, "they shall be holy to their God" (Leviticus 21:6) - therefore, He distanced them from the dead. And I have already written above (Sefer HaChinukh 159) that the substance of impurity is something that is disgusting and vile. And the Sages explained about the body of a dead person that it is the primary source of the primary sources (avi avot) of impurity - meaning to say that it has very strong impurity, above all [other] impurity. And the matter is that in the separation from him of the living, good form of the intellect, [the body] remains by itself, as 'he is also only flesh' - base and inferior, and seeking evil things; and also in its great evil, it led the precious soul to sin when it was still dwelling with it. Hence it is fitting that it make impure all that is around it, in the stripping of its glory from it - and that is the soul - and [when] only the evil substance remains in it. And it is truly fitting that the servants of God, may He be blessed, distance themselves from it - except for the relatives that are permitted to them, as they are their brothers, their flesh. As all the ways of the Torah 'are pleasant and its paths are peace,' and it did not want to grieve them so much. As their hearts would be heated about the dead relative, that they could not approach into the tent that he is in and pour out their spirits and satiate their souls with crying about him. And I saw a hint about the reason which I wrote about the impurity of the dead; as they, may their memory be blessed, said (Talmud Yerushalmi Berakhot 3:1) that the completely righteous do not render impure. And from what appears, the intention is [that it is] because their bodies are pure and clean and they did not bring their soul to sin, but [rather] aided it to receive merit. And therefore their soul rose in a 'kiss,' and upon their cadaver sown light will shine forever.

That a priest who immersed that day (tevul yom) not serve until his sun set: That a priest who immersed that day not serve until his sun sets. And even though he immersed and became pure, he needs the setting of the sun - since he is like a secondary impurity until his sun sets. As so did they, may their memory be blessed, explain, "it shall be brought into water and be impure until evening and become pure" (Leviticus 11:32): The verse called one who immersed that day impure, even though he immersed, until his sun set (Mishneh Torah, Laws of Other Sources of Defilement 10:1). But nonetheless he is not impure like he was before the immersion. As at the beginning, he was a primary impurity and after the immersion he is called a secondary impurity. And about this is it stated (Leviticus 21:6), "and they shall not desecrate the name of their God." As so did the received explanation come about it, and so is it in the ninth chapter of Sanhedrin 83b. As there they said, "'Holy shall they be to their God, and they shall not desecrate the name of their God'; if it is not regarding one impure - as it was already elucidated (Sefer Hachinukh 178) - teach it for the matter of the one who has immersed on that day." And it is learned over there from [the inferential comparison] of "desecration" [and] "desecration."