The meat that was left until the third day was considered as tainted (piggûl). In Hebrew, the term is derived from a verb that means “to rot.” It may reflect the fact that by the third day, the meat will have become rancid and spoiled (see Leviticus 19:7; Isaiah 65:4; Ezekiel 4:14).
18 If any of the flesh of the sacrifice of his peace offering is eaten on the third day, he who offers it shall not be accepted, neither shall it be credited to him. It is tainted, and he who eats of it shall bear his iniquity.