Leviticus 17:2

Speak with Aharon and with his sons, and with the sons of Israel, and tell them: This is the word which the Lord hath commanded, saying:

Tell Aaron and his sons for they constitute Israel’s ritual slaughterers.

SPEAK UNTO AARON, AND UNTO HIS SONS, AND UNTO ALL THE CHILDREN OF ISRAEL. Since this section contains the warning that all offerings are to be brought only in the Tent of Meeting [i.e., in the Sanctuary Court], He therefore admonishes the priests who perform the rites of the offerings that they are not to perform the rites outside [the Sanctuary Court], and He also admonishes the Israelites that they should bring them there to G-d, and not offer them outside by themselves.
The correct interpretation of this section is as our Rabbis have mentioned, that He forbade Israel whilst in the desert to eat an ordinary meal of meat [i.e., one which was not part of an offering], and they were to eat only the meat of peace-offerings [the fat portions and the blood of which] had been offered upon the altar of G-d. Therefore He said that whoever wants to slaughter any of the three kinds of animals from which all offerings are brought, namely, the ox, lamb, and goat, must bring them unto the door of the Tent of Meeting, and make them offerings of peace-offerings, bringing the fats and the blood upon the altar of G-d, and then he may eat the meat thereof according to the law [of peace-offerings, which is that the priest is given the breast and the right thigh, and the rest of the meat is eaten by the owner and his family for two days and the intervening night]. He further stated that if he slaughtered them in any other place, he is liable to the punishment of excision.. See Ramban further, 18:29 for the specific meaning of this form of punishment.
It appears likely from the language of Scripture that at first [i.e., in Verse 3-7] He declared a person liable to the punishment of excision in the case of any slaughtering outside [the Sanctuary Court] even of unconsecrated animals, this being the prohibition against eating an ordinary meal of meat, and He stated that the reason for it is so that they should consecrate them to G-d and the priest shall sprinkle the blood upon the altar of the Eternal and burn on it the fat. Afterwards [in Verses 8-9] He warned against making an altar to G-d outside [the Sanctuary Court] and offering on it the peace-offerings mentioned [in Verse 5] or a burnt-offering, as used to be done with holy offerings at the time when the bamoth, Note 122 for full explanation of this term. were permitted, but they were to offer them to G-d in front of the door of the Tent of Meeting. Thus He ordered all …

זה הדבר, when the Torah said in 15,31 והזהרתם את בני ישראל מטומאתם, “you are to warn the Israelites regarding their state of ritual contamination,” the warning implied that they were to separate themselves from spiritually negative influences represented both by ritual contamination and by demons.