Jamieson, Fausset and Brown on Leviticus 7:15-17

15-17. the flesh of the sacrifice of his peace offerings ... shall be eaten the same day that it is offered--The flesh of the sacrifices was eaten on the day of the offering or on the day following. But if any part of it remained till the third day, it was, instead of being made use of, to be burned with fire. In the East, butcher-meat is generally eaten the day it is killed, and it is rarely kept a second day, so that as a prohibition was issued against any of the flesh in the peace offerings being used on the third day, it has been thought, not without reason, that this injunction must have been given to prevent a superstitious notion arising that there was some virtue or holiness belonging to it.