Leviticus 3:5

And Aaron’s sons. — After the offerer has killed the victim, taken out the choice parts and offered them to the officiating priest, the latter shall burn it, that is, the whole collection of the fat pieces described in Leviticus 3:3, upon the ashes of the continual burnt offering, which was the daily offering of the lamb. It had always the precedence, and was burning the whole day (Leviticus 6:12). Besides these choice pieces which had thus to be burnt, the breast and the right shoulder were reserved for the priest, whilst the remainder of the peace offering was eaten by the offerer, his family and his friends (Leviticus 7:15).