Leviticus 19:7

And if it be eaten at all on the third day, it is abominable; it shall not be accepted.

The peace offering was to have none of it eaten on the third day. Eating any of it at all on that day made the offering abominable. So eaten, it would not be accepted.

Whoever ate of it on the third day bore guilt for profaning what is holy. That person was to be cut off from the people. To be accepted and approved, people must be holy as God is holy. That holiness is practiced godliness in every circumstance toward all who need mercy and relief, not only toward one's own group. It means loving one's neighbor as oneself, beginning as a blessing in one's own family. It is carried out by daily putting away selfishness and self-centeredness and cultivating the attributes of Jesus, which are the attributes of God. Each believer united with Christ is called to grow individually to the full stature of Christ, since church membership itself does not save.