10 “Juda is my king: Moab the pot of my hope”. What Juda? He that is of the tribe of Juda. What Juda, but He to whom Jacob himself said, “Juda, your brethren shall praise you”? What therefore should I fear, when Juda my king says, “Fear not them that kill the body”? “Moab the pot of my hope.” Wherefore “pot”? Because tribulation. Wherefore “of my hope”? Because there has gone before Juda my king....Moab is perceived in the Gentiles. For that nation was born of sin, that nation was born of the daughters of Lot, who lay with their father drunken, abusing a father. Better were it to have remained barren, than thus to have become mothers. But this was a kind of figure of them that abuse the law. For do not heed that law in the Latin language is of the feminine gender: in Greek of the masculine gender it is: but whether it be of the feminine gender in speaking, or of the masculine, the expression makes no difference to the truth. For law has rather a masculine force, because it rules, is not ruled. But moreover, the Apostle Paul says what? “Good is the law, if any one use it lawfully.” But those daughters of Lot unlawfully used their father. But in the same manner as good works begin to grow when a man uses well the law: so arise evil works, when a man ill uses the law. Furthermore, they ill using their father, that is, ill using the law, engendered the Moabites, by whom are signified evil works. Thence the tribulation of the Church, thence the pot boiling up. Of this pot in a certain place of prophecy is said, “A pot heated by the North wind.” Whence but by the quarters of the devil, who has said, “I will set my seat at the North”? The chiefest tribulations therefore arise against the Church from none except from those that ill use the law....
11. “Into Idumæa I will stretch out my shoe”. The Church speaks, “I will come through even unto Idumæa.” Let tribulations rage, let the world boil with offenses, even unto those very persons that lead an earthly life (for Idumæa is interpreted earthly), even unto those same, “even unto Idumæa, I will stretch out my shoe.” Of what thing the shoe except of the Gospel? “How beautiful the feet of them that tell of peace, that tell of good things,” and “the feet shod unto the preparation of the Gospel of peace.”...In these times we see, brethren, how many earthly men do perpetrate frauds for the sake of gain, for frauds perjuries; on account of their fears they consult fortune-tellers, astrologers: all these men are Edomites, earthly; and nevertheless all these men adore Christ, under His own shoe they are; now even unto Idumæa is stretched out His shoe. “To Me Allophyli have been made subject.” Who are “Allophyli”? Men of other race, not belonging to My race. They “have been made subject,” because many men adore Christ, and are not to reign with Christ.
12. “Who will lead Me down into the city of standing round?”. What is the city of standing round? If you remember already, I have made mention thereof in another Psalm, wherein has been said, “And they shall go around the city.” For the city of standing round is the compassing around of the Gentiles, which compassing around of the Gentiles in the middle thereof had the one nation of the Jews, worshipping one God: the rest of the compassing around of the Gentiles to idols made supplication, demons they did serve. And mystically it was called the city of standing round; because on all sides the Gentiles had poured themselves around, and had stood around that nation which did worship one God....“Who will lead me down even unto Idumæa?”
13. “Wilt not Thou, O God, that hast driven us back? And will not Thou, O God, march forth in our powers?”. Wilt not Thou lead us down, that hast driven us back? But wherefore “hast driven us back”? Because You have destroyed us. Wherefore hast destroyed us? Because angry You have been, and hast had pity on us. Thou therefore wilt lead down, that hast driven back; Thou, O God, that will not march forth in our powers, wilt lead down. What is, “will not march forth in our powers”? The world is to rage, the world is to tread us down, there is to be a heap of witnesses, built of the spilled blood of martyrs, and the raging heathen are to say, “Where is the God of them?” Then “You will not march forth in our powers:” against them You will not show Yourself, You will not show Your power, such as You have shown in David, in Moses, in Joshua the son of Nun, when to their might the Gentiles yielded, and when the slaughter had been ended, and the great laying waste repaired, into the land which Thou promised Thou leddest in Your people. This thing then You will not do, “You will not march forth in our powers,” but within You will work. What is, “will not march forth”? Wilt not show Yourself. For indeed when in chains the Martyrs were being led along, when they were being shut up in prison, when they were being led forth to be mocked, when to the beasts they were exposed, when they were being smitten with the sword, when with fire they were being burned, were they not despised as though forsaken, as though without helper? In what manner was God working within? In what manner within was He comforting? In what manner to these men was He making sweet the hope of life everlasting? In what manner was He not forsaking the hearts of them, where the man was dwelling in silence, well if good, ill if evil? Was He then by any means forsaking, because He was not marching forth in the powers of them? By not marching forth in the powers of them, did He not the more lead down the Church even unto Idumæa, lead down the Church even unto the city of standing around? For if the Church chose to war and to use the sword, She would seem to be fighting for life present: but because she was despising life present, therefore there was made a heap of witness for the life that shall be.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)