Charles Ellicott Commentary Leviticus 7:17

"but that which remaineth of the flesh of the sacrifice on the third day shall be burnt with fire." — Leviticus 7:17 (ASV)

But the remainder of the flesh. —If, however, the sacrifices were very plentiful, or if through stinginess of the owners a sufficient number of poor guests were not invited, so that the victim could not be eaten up within the time specified, all that remained on the third day was to be burned.