John Gill Commentary Leviticus 10:15

"The heave-thigh and the wave-breast shall they bring with the offerings made by fire of the fat, to wave it for a wave-offering before Jehovah: and it shall be thine, and thy sons` with thee, as a portion for ever; as Jehovah hath commanded." — Leviticus 10:15 (ASV)

The heave shoulder and wave breast shall they bring
Not the priests, but the owners to the priests, (Leviticus 7:29Leviticus 7:30):

with the offerings made by fire of the fat:
upon the inwards, kidneys, and caul of the liver, which was all burnt:

to wave [it] for a wave offering before the Lord,
the shoulder was lifted up, and the breast waved to and fro before the Lord of the whole earth, and towards the several parts of it, to show and own his right to all they had, and then they were given to the priests as a token of it:

and it shall be yours, and your sons with you;
both the shoulder and the breast:

by a statute for ever,
to be observed as long as the ceremonial law and Levitical priesthood lasted, even to the end of the Jewish age and economy, and the coming of the Messiah:

as the Lord has commanded;
(Leviticus 7:33Leviticus 7:34).