Midrasch zu Bamidbar 6:19

5) (Vayikra 7:34) ("For the breast of the tenufah and the shok of the terumah have I taken from the children of Israel from the sacrifices of their peace-offerings, and I have given them to Aaron the Cohein and to his sons as an everlasting statute from the children of Israel.") "the breast": This is the breast (itself); "hatenufah": This is (to include as reverting to the Cohein what is added in the offering of the ram of the Nazirite in) the tenufah of the basket (viz. Numbers 6:19). "shok": This is the shok itself. "haterumah": This is (to include as reverting to the Cohein the terumah of the four challoth of the thanksgiving offering (viz. Vayikra 7:14). "have I taken from the children of Israel": They should have reverted to the (first-born of the) Israelites, (who were originally slated to be the priests), but when they sinned (with the golden calf), they were taken from them and given to the Cohanim. I might think that just as they were taken from them because they sinned, so they will be restored to them (in the future, when their sin is atoned). It is, therefore, written "and I have given them to Aaron the Cohein and to his sons as an everlasting statute" — They are given to the Cohein as an everlasting gift.

(Bamidbar 6:19) "And the Cohein shall take the cooked ("beshelah") shoulder of the ram": "beshelah" connotes "whole" (i.e., it is first cooked and then separated from the ram.) R. Shimon b. Yochai says: "beshelah" implies only that it must be cooked together with the ram, (but it is separated before the cooking.) "and one unleavened cake": If it were broken or part were missing, it is invalid. "and one unleavened wafer": If it were broken or part were missing it is invalid. "and he shall place them on the palms of the Nazirite after his shaving of (the head of) his Naziritism.": This is after his shaving, but the bringing of the offerings is not after his shaving.