Leviticus 7:28-36

GOD spoke to Moses: “Speak to the People of Israel. Tell them, When you present a Peace-Offering to GOD, bring some of your Peace-Offering as a special sacrifice to GOD, a gift to GOD in your own hands. Bring the fat with the breast and then wave the breast before GOD as a Wave-Offering. The priest will burn the fat on the Altar; Aaron and his sons get the breast. Give the right thigh from your Peace-Offerings as a Contribution-Offering to the priest. Give a portion of the right thigh to the son of Aaron who offers the blood and fat of the Peace-Offering as his portion. From the Peace-Offerings of Israel, I’m giving the breast of the Wave-Offering and the thigh of the Contribution-Offering to Aaron the priest and his sons. This is their fixed compensation from the People of Israel.” From the day they are presented to serve as priests to GOD, Aaron and his sons can expect to receive these allotments from the gifts of GOD. This is what GOD commanded the People of Israel to give the priests from the day of their anointing. This is the fixed rule down through the generations.