17 The Psalm then continues: “His delight was in cursing, and it shall happen to him”. Although Judas loved cursing, both in stealing from the money bag, and selling and betraying the Lord: nevertheless, that people more openly loved cursing, when they said, “His blood be on us, and on our children.” “He loved not blessing, therefore it shall be far from him.” Such was Judas indeed, since he loved not Christ, in whom is everlasting blessing; but the Jewish people still more decidedly refused blessing, unto whom he who had been enlightened by the Lord said, “Will ye also be His disciples?” “He clothed himself with cursing, like as with a raiment:” either Judas, or that people.
“And it came into his bowels like water.” Both without, then, and within; without, like a garment; within, like water: since he has come before the judgment-seat of Him “who has power to destroy both body and soul in hell;” the body without, the soul within. “And like oil into his bones.” He shows that he works evil with delight, and stores up cursing for himself, that is, everlasting punishment; for blessing is eternal life. For at present evil deeds are his delight, flowing like water into his bowels, like oil into his bones; but it is styled cursing, because God has appointed torments for such men.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)