7 Well, who sell oxen? They who have dispensed to us the Holy Scriptures are understood to mean the oxen. The apostles were oxen, the prophets were oxen. Whence the apostle says: “You shall not muzzle the mouth of the ox that treads out the grain. Does God take care for oxen? Or says He it for our sakes? Yea, for our sakes He says it: that he who plowes should plow in hope; and he that threshes, in hope of partaking.” Those oxen, then, have left to us the narration of the Scriptures.
For it was not of their own that they dispensed, because they sought the glory of the Lord. Now, what have ye heard in that psalm? “And let them say continually, The Lord be magnified, they that wish the peace of His servant.” God's servant, God's people, God's Church. Let them who wish the peace of that Church magnify the Lord, not the servant: “and let them say continually, The Lord be magnified.” Who, let say? “Them who wish the peace of His servant.” The voice of that people, of that servant, is clearly that voice which you have heard in lamentations in the psalm, and were moved at hearing, because you are of that people.
What was sung by one, re-echoed from the hearts of all. Happy they who recognized themselves in those voices as in a mirror. Who, then, are they that wish the peace of His servant, the peace of His people, the peace of the one whom He calls His “only one,” and whom He wishes to be delivered from the lion: “Deliver mine only one from the power of the dog?” They who say always, “The Lord be magnified.” Those oxen, then, magnified the Lord, not themselves. See this ox magnifying his Lord, because “the ox knows his owner;” observe that ox in fear lest men desert the ox's owner and rely on the ox: how he dreads them that are willing to put their confidence in him: “Was Paul crucified for you?
Or were ye baptized in the name of Paul?” Of what I gave, I was not the giver: freely you have received; the dove came down from heaven. “I have planted,” says he, “Apollo, watered; but God gave the increase: neither he that plants is anything, neither he that waters; but God that gives the increase.” “And let them say always, The Lord be magnified, they that wish the peace of His servant.”
Source: Tractates on the Gospel of John (New Advent)