Leviticus 22:10

10There shall no stranger. It was also necessary to add this, that the majesty of sacred things might not be impaired; for if it had been promiscuously permitted to all to eat of the sacred bread and the other oblations, the people would have straightway inferred that they differed not from ordinary food. And unless the avarice of the priests had been thus anticipated, (195) an unworthy trade would have prevailed; for banquets would have been see up for sale, and the priest’s house would have been a kind of provision-market. The prohibition, therefore, that the meats offered in sacrifice should be eaten by strangers, was not made so much with reference to them as to the priests, who would have else driven a profitable trade with the offerings, or, by gratifying their guests, would not have hesitated to bring disrepute on the whole service of God. The Law consequently prohibits that either a sojourner, or a hired servant, should eat of them; and only gives this permission to their slaves, and those who were incorporated into their families. Moreover, He counts the priests’ daughters who had married into another tribe as aliens. The sum has this tendency, that whatsoever depends on the service of God should obtain its due reverence; nor could this be the case, if what was offered in the temple were not distinguished from common food. Inasmuch as they were human beings, they were allowed to subsist in the ordinary manner; yet was this distinction necessary, which might savor of the sanctity of Christ. This was the cleanness of the priests as regarded food.