But also Tobias the Ammonite, his neighbor, said: Let them build, etc. And both the person and words of this Tobias agree with heretics. The person indeed, because his patriarch Ammon was conceived from incest and drunkenness, and at night and in a cave. All of which clearly can be easily applied to any heresiarch; whose entire origin is from carnal pleasure and impurity, from the darkness of errors or crimes, from private gatherings, and not from the public symbol of the holy Church. Indeed, Tobias himself, meaning "good" of the Lord, said not by merit and truth, but by arrogance and pride, that the wall of the holy city could be leaped over by a fox; it is evident that heretics are called foxes. From which is that of the Song of Songs: Catch for us the little foxes that ruin the vineyards (Cant. II); which is to say quite clearly, Catch and bring to light the putrid and deceitful cunning of heretics, by which they strive to corrupt the fruitful minds of the faithful. Therefore, if, he says, a fox climbs up, it will leap over their stone wall. If against their faith's assertion any heretic arises, he immediately becomes proud and will subject all the confidence of their doctrine to his feet, which they boast is fortified like a stone and founded in Christ. But such blasphemers will come to what the sacred writer of this history, in imprecation, adds:
Source: Commentary on Ezra and Nehemiah