Leviticus 7:30, commentary and pictures

Each person was required to bring the Lord's offering with his own hands, a duty that could not be performed by someone else on his behalf. This is the law of the peace offerings, which were especially an expression of thanksgiving to God. The one bringing the offering was to bring its fat with the breast before the Lord, so that the breast might be waved for a wave offering.

The fat belonged to God alone, was to be burned upon the altar to Him first, and was not to be eaten. The breast and right shoulder, with certain smaller specified portions, were allotted to and reserved for the priests. The remaining and greater part of the meat was returned to the offerer to be eaten by him and his friends in a sacrificial feast.

The priests had no right to take their portion before the fat had been separated and offered to God, so to demand more than the allotted priestly part and to refuse to wait until the fat was burned was a violation. Such misuse turned the solemn symbolic service into self-indulgence. The sacrifices pointed forward to the death of Christ and were designed to preserve faith in the coming Redeemer, directing all hearts in gratitude and faith to the great Sacrifice that takes away the sin of the world. Because of that forward-pointing purpose, the directions had to be strictly heeded in the most solemn manner.