Leviticus 17:2

Speak unto Aaron, and unto his sons
Who were now constituted priests, the business of whose office it was to offer the sacrifices of the people, ordinary and extraordinary: and to all the children of Israel;
who were all under obligation to sacrifices at certain times; under whom may be comprehended the Levites, who were not priests, and the strangers that sojourned in Israel, for these are concerned in the following law: and say unto them;
which is spoken to Moses, who was to say what follows to Aaron, and by him to his sons, and by his sons to the people of Israel, and by them to the strangers: this [is] the thing which the Lord hath commanded;
ordered to be observed as his will and pleasure by everyone of them: saying;
namely, what follows.