Leviticus 6:23

It shall not be eaten No part of it shall be eaten by the priest, as it was when the offering was for the people. The reason of the difference is, partly because when he offered it for the people, he was to have some recompense for his pains; partly to signify the imperfection of the Levitical priests, who could not bear their own iniquity; for the priest's eating part of the people's sacrifice did signify his typical bearing of the people's iniquity; and partly to teach the priests and ministers of God, that it is their duty to serve God with singleness of heart, and to be content with God's honour, though they have no present advantage by it.