That they take for me an offering (Exod. 25:2). May it please our masters to teach us: What did they do with the surplus offering? Thus did our masters teach us: They fashioned with it the hammered gold overlay for the Holy of Holies. You find that the Holy One, blessed be He, chose two offerings (terumot): the offering (set aside) for the building of the Tabernacle and the priestly offering. The priestly offering (was given to them) in order that they become students of the law. R. Yannai said: Any priest who is not a student of the law, it is permitted to eat the offering on his grave.
R. Isaac said in the name of R. Johanan: Observe what is written in the verse: The priests have done violence to My law, and have profaned My holy things (Ezek. 22:26). How did they do that? They have not distinguished between the holy and the common, neither have they taught differences between the unclean and the clean (ibid.). If the priest is not a student of the Torah, he is unable to distinguish between the holy and the profane, the unclean and the clean. Therefore Scripture says: Thou hast despised My holy things and hast profaned My Sabbaths (ibid., v. 18). Why does he despise the holy things? Because he does not know how to observe the Sabbath. See how beloved is the priestly offering in that it was given to the priests who were students of the law. But the Holy One, blessed be He, decreed the Temple offering for His own sake, as it is said: That they take for me an offering.