"On the eighth day, he is to take two lambs without defect, a one year old ewe lamb without defect, one third of a measure of fine flour mixed with olive oil for a meal offering, and one log of oil.

If any of the meat of his sacrifice of peace offerings is eaten on the third day, it won't be accepted for the one who brought it. It is to be considered as refuse, and whoever eats it will bear the punishment of his iniquity."

but whatever remains uneaten from the meat of the sacrifice by the third day is to be incinerated.

Your sacrifice is to be eaten on that day and the next day. Anything that remains to the third day is to be incinerated.

If it is eaten on the third day, it's unclean. It won't be accepted.