11 What does he mean to express by the “thigh”? The flesh. Whence those words, “A prince shall not depart from Judah; and a lawgiver from his thighs”? Did not Abraham himself (to whom was promised the seed in which “all the nations of the earth were to be blessed”), when he sent his servant to seek and to bring home a wife for his son, being by faith fully persuaded, that in that, so to speak, contemptible seed was contained the great Name; that is, that the Son of God was to come of the seed of Abraham, out of all the children of men; did not he, I say, cause his servant to swear unto him in this manner, saying, “Put your hand under my thigh,” and so swear; as if he had said, “Put your hand on the altar, or on the Gospel, or on the Prophet, or on any holy thing.” “Put” (he says) “your hand under my thigh;” having full confidence, not ashamed of it as unseemly, but understanding therein a truth. “With Your beauty and Your glory.” Take to You that righteousness, in which You are at all times beautiful and glorious. “And speed on, and proceed prosperously, and reign”. Do we not see it so? Is it not already come to pass? He has “sped on; has proceeded prosperously, and He reigns;” all nations are subdued unto Him. What a thing was it to see that “in the Spirit,” of which same thing it is now in our power to experience in the reality! At the time when these words were said, Christ did not yet “reign” thus; had not yet sped on, nor “proceeded prosperously.” They were then being preached, they have now been fulfilled: in many things we have God's promise fulfilled already; in some few we have to claim its fulfilment yet.
12. “Because of truth, meekness, and righteousness.” Truth was restored unto us, when “the Truth sprung out of the earth: and Righteousness looked out from heaven.” Christ was presented to the expectation of mankind, that in Abraham's Seed “all nations should be blessed.” The Gospel has been preached. It is “the Truth.” What is meant by “meekness”? The Martyrs have suffered; and the kingdom of God has made much progress from thence, and advanced throughout all nations; because the Martyrs suffered, and neither “fell away,” nor yet offered resistance; confessing everything, concealing nothing; prepared for everything, shrinking from nothing. Marvellous “meekness”! This did the body of Christ, by its Head it learned. He was first “led as a sheep to the slaughter, and as a lamb before his shearer is dumb, even so opened not His mouth;” meek to that degree, that while hanging on the Cross, He said, “Father, forgive them, for they know not what they do.” Why because of “righteousness”? He will come also to judge, and to “render to every man according to his works.” He spoke “the truth;” He patiently endured unrighteousness: He is to bring “righteousness” hereafter.
13. “And Your right hand shall lead You on marvellously.” We shall be guided on by His right hand: He by His own. For He is God, we mortal men. He was led on by His own right hand; i.e. by His own power. For the power which the Father has, He has also; the Father's immortality He has also; He has the Father's Divinity, the Father's Eternity, the Father's Power. Marvellously will His right hand lead Him on, performing the works of God; undergoing human sufferings, overthrowing the evil wills of men by His own goodness. Even now, He is being led on even to places where as yet He is not; and it is His own right hand that is leading Him on. For that is leading Him there which He has Himself bestowed upon His Saints. “Your right hand shall lead You on marvellously.”
14. “Your arrows are sharp, are most powerful”; words that pierce the heart, that kindle love. Whence in the Song of Songs it is said, “I am wounded with love.” For she speaks of being “wounded with love;” that is, of being in love, of being inflamed with passion, of sighing for the Bridegroom, from whom she received the arrow of the Word. “Your arrows are sharp, are most powerful;” both piercing, and effective; “sharp, most powerful.” “The peoples shall fall under You.” Who have “fallen”? They who were “wounded” have also “fallen.” We see the nations subdued unto Christ; we do not see them “fall.” He explains where they “fall,” viz. “in the heart.” It was there they lifted themselves up against Christ, there they “fall” down before Christ. Saul was a blasphemer of Christ: he was then lifted up, he prays to Christ, “he is fallen,” he is prostrate before Him: the enemy of Christ is slain, that the disciple of Christ may live! By an arrow launched from heaven, Saul (not as yet Paul, but still Saul), still lifted up, still not yet prostrate, is wounded in “the heart:” he received the arrow, he fell “in heart.” For though he fell prostrate on his face, it was not there that he fell down in heart: but it was there where he said aloud, “Lord, what dost Thou bid me do?” But just now thou were going to bind the Christians, and to bring them to punishment: and now you say unto Christ, “What dost Thou bid me do?” O arrow sharp and most mighty, by whose stroke “Saul” fell, so as to become “Paul.” As it was with him, so was it also with “the peoples;” consider the nations, observe their subjection unto Christ. “The peoples” (then) “shall fall under You in the heart of the King's enemies;” that is, in the heart of Your enemies. For it is Him that he calls King, Him that he recognises as King. “The peoples shall fall under You in the heart of the King's enemies.” They were “enemies” before; they have been stricken by your arrows: they have fallen before You. Out of enemies they have been made friends: the enemies are dead, the friends survive. This is the meaning of, “for those which shall be changed.” We are seeking to “understand” each single word, and each separate verse; yet so far only are we to seek for their “understanding,” as to leave no one to doubt that they are spoken of Christ.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)