12 But this thing is not granted to believing Jews alone....“The eyes of Him do look upon the Gentiles.” And what do we? The Jews will murmur; the Jews will say, “what He has given to us, the same to them also; to us Gospel, to them Gospel; to us the Grace of Resurrection, and to them the Grace of Resurrection; does it profit us nothing that we have received the Law, and that in the justifications of the Law we have lived, and have kept the commandments of the fathers?
Nothing will it avail? The same to them as to us.” Let them not strive, let them not dispute. “Let not them that are bitter be exalted in their own selves.” O flesh miserable and wasting, are you not sinful? Why cries out your tongue? Let the conscience be listened to. “For all men have sinned, and need the glory of God.” Know yourself, human weakness. You received the Law, in order that a transgressor also of the Law you might be: for you have not kept and fulfilled that which you received.
There has come to you because of the Law, not the justification which the Law enjoins, but the transgression which you have done. If therefore there has abounded sin, why do you envy Grace more abounding. Be not bitter, for “let not them that are bitter be exalted in their own selves.” He seems in a manner to have uttered a curse in “Let not them that are bitter be exalted;” yea, be they exalted, but not “in themselves.” Let them be humbled in themselves, exalted in Christ. For, “he that humbles himself shall be exalted; and he that exalts himself shall be humbled.” “Let not them that are bitter be exalted in their own selves.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)