Parsha Mitzvot: Tzav: Mitzvah 145 – Concept 393
“If his feast-offering is for a vow or a donation, it must be eaten on the day he offered his feast-offering; and on the next day, what is left over may be eaten. What is left over from the flesh of the feast-offering shall be burned in the fire on the third day. And if some of the flesh of his feast thanksgiving peace-offering was intended to be eaten on the third day, it is not acceptable, the one who offers it may not intend this; it remains Pigul, rejevted, and the soul that eats it shall bear its iniquity (Vayikra 7:16-18). We may not eat from sacrifices offered with improper intentions (Rambam, Hilchot Pesulei ha-Mukdashim – The Laws of Disqualified Offerings).
The verse speaks of someone who, while performing the blood service, intended that the offering would be consumed after the prescribed time limit.
Everything else about this offering was done properly, but, in a fleeting moment, a quick intention occurs to the one performing the blood service, and that thought has such power that the Korban is rejected, and one is liable for Karet, excision of the soul, for eating of it! This is the power of a thought! This is the importance of proper intention while performing a Mitzvah! (Metzudat David)