Or HaChaim on Exodus 29:27/אור החיים על שמות כ״ט:כ״ז

1 מאשר לאהרון ומאשר לבניו. "of that which is Aaron's and of that which is his sons'". Why was this phrase needed at all? Perhaps the Torah meant to inform us that Moses was allowed to eat these parts only in this instance. He would not be permitted to eat of the breast or thigh of any other sacrificial offerings in the future, they would be exclusively Aaron's and his sons.