And the flesh of the sacrifice of his peace-offerings for thanksgiving shall be eaten on the day of his oblation; he shall not leave any of it until the morning
Why such detail in the law of Moses? Why, if the priests are full, cannot they keep some of the meat for breakfast? They would not be eating pork sausage after all.
Some interpret this to be in contrast with other local customs regarding sacrificial foods. The left-overs became used for telling the future, a kind of horoscope. God would have his people separate themselves from these practices. God would have his people understand the holiness of God. The holiness of God is not some thing within itself, which is what all people are tempted to treat it as. We would think of something holy as retaining some feature of special power to benefit us. Examples include using holy water to ward off bad luck, keeping bibles around the house in hopes of bringing good luck. I recall in Liberia when I did a medical rotation there. Some women would keep an open bible on the bed after delivering their babies in the hospital, as a kind of talisman, even if they couldn't read it. And of course countless incidences of people through the ages collecting supposed pieces of Jesus’ cross, images of him on clothes, dirt from Jerusalem, etc. bear witness to this tendency of the human heart.
But this is the kind of thing that God is teaching his people to avoid. To treat the holiness of God as some sort of talisman belittles God and detracts from God. It tries to put the king of the universe at our beck and call. This “god-on-a-stick” philosophy promises great gains to those who invest, who purchase enough god points. It is really simply breaking the no-God-but-me commandments from Exodus 20:1-6. For the King of the Universe does not come on a stick. He cannot be served up just for you, with the flavors you like, and no onions.
Those of us with those tendencies (which is all the people I have ever known, myself included), must embark on a change to approach the one true God: we must be like Peter when he saw Jesus walking on the water. He did not jump out and run over to him. But rather he called out: “Lord, if it be thou, bid me come unto thee upon the waters” (Matt 14:28). Peter realized that the call of God is the only rational approach to God. It is not we who go to the god-buffet table and put together whatsoever kind of God we would prefer. It is God who must come to us, to call us into relation with him.
And this call of God is holy. For God is holy. Set apart from the common, set apart from this world is God. Unreachable in his glory and holiness, what hope do we have of ever being accepted into His presence? If we cannot ask this question, we have not come to understand the call of God. For only after trying and failing do we find our need for God. And only then can we understand a small glimpse of the gift that God gave us in the person of Jesus Christ.