Both what dies of itself
and what is torn by beasts
have already been prohibited in Leviticus 17:15. In this instance the restriction is repeated for emphasis among the priesthood. They were allowed to eat the holy food, and so the restriction is more stringent in this command.
7 après le coucher du soleil, il sera pur, et il mangera ensuite des choses saintes, car c'est sa nourriture.