1 Samuel 21:5

"Today it shall be sanctified because of the vessels" — he said this rather obscurely, but it means this: "My young men have been sanctified and have kept themselves from a woman both yesterday and the day before" — for this is what his saying that the young men were purified amounts to. And if it were not so, in any case it would be sanctified through the eating of the bread of the setting-forth. Persuaded by what was said, the priest gives David some of the loaves, which none other ought to eat except the priests alone. And this belongs to the prophecy that reveals through deeds: that, although the royal tribe was one, that is, that of Judah, and the priestly tribe was another, I mean the Levitical, the priestly dignity and the royal were going to be joined together and made one in the coming of our Savior descended from David, priest and king at once, the one "according to the order of Melchizedek."

And David answered the priest, and said to him: Indeed, if it concerns women, etc. He answered those sending forth the apostles to teach the nations: What God has purified, do not call common (Acts X). For the Church restrained itself with my present help from idolatry and other crimes, from the time when it emerged through confession from the hiding place of ancient blindness, until it came to the light of knowing the holy Trinity, which is God; and the hearts of the humble were holy through the renunciation of Satan. Moreover, this manner of life, which is lived among the nations, is polluted, not yet purified, sanctified, and justified by those being catechized through the fountain of regeneration and the grace of the Spirit; but the very light of present reconciliation will sanctify it in those who receive baptism with a devout heart. It should truly be noted, according to the letter, how cautiously and wisely David either questioned the priest, or responded to the priest about his own and his followers' purity. For he not only inquired if the boys could receive the holy bread if they were clean from women, but also examined if they were clean from all pollution, which typically happens to mortals, especially concerning the contamination of womanly coupling, as if investigating matters greater than others. For indeed, this is the greatest of those things which, though they do not make people guilty by fault, yet deter them from the touch of the saints through the impurity of any kind, for example, the touch of a dead body, or of a reptile. But David, not without discernment, examining himself and his followers, asserts that they abstained from the embrace of a wife, carefully explaining the duration of the same abstinence. He testifies that all the utensils of the boys are holy, that is, their weapons, clothes, and even the small vessels they carried for likely provisions were clean from the contamination of any filth. And because he knew that what was consecrated to divine ministries was not to be transferred to common use without great discernment, so that he would hide nothing of his state from the priest who was a steward of these things, he says only that the road by which they had come was polluted, evidently with some funerary object lying on it, or by being unclean itself. But he also says that today it will be sanctified in the vessels; that…