Leviticus 8:29

The sacrifice having been offered Moses waves the breast and it is reserved as his portion. It has been asked Why, if Moses receives the breast as a priestly due, does he not also receive the right thigh and cakes? In answer it may be said that the whole ceremony is twofold in character. It is an inauguration of the priesthood and at the same time an instruction to the future priests how they should discharge their functions. The ceremony of waving the breast being prescribed for all Peace-Offerings is observed by Moses. The inauguration of the priests, both as offerers of sacrifice and receivers of priestly dues, is indicated by the composite character of that which is placed in their hands, and the first Wave-Offering is given entirely to the Lord to shew that all belongs to Him and that He is the real giver of the priestly dues or, as it is said, He -is their inheritance." (Deuteronomy 18:2.)