TT points to the assignment of the right thigh as terumah to the Kohen and the perpetual statute of breast + thigh.
ואת שוק הימין תתנו תרומה לכהן מזבחי שלמיכם — שוק הימין ניתן לכהן. חזה התנופה ושוק התרומה — לכהנים לחק עולם.
“And the right thigh you shall give as a contribution to the priest from your peace-offerings” — the right thigh is given to the Kohen. “The breast of the wave-offering and the thigh of the contribution” — they belong to the Kohanim as a perpetual statute.
Custom — assignment of the priestly gifts.
From every shelamim the right thigh is given to the Kohen as terumah, and together with the waved breast it becomes a perpetual statute for Aharon and his sons.