1 This Psalm is addressed “to the sons of Korah,” as its title shows. Now Korah is equivalent to the word baldness; and we find in the Gospel that our Lord Jesus Christ was crucified in “the place of a skull.” It is clear then that this Psalm is sung to the “sons of His 'Passion.'” Now we have on this point a most certain and most evident testimony from the Apostle Paul; because that at the time when the Church was suffering under the persecutions of the Gentiles, he quoted from hence a verse, to insert by way of consolation, and encouragement to patience. For that which he inserted in his Epistle, is said here: “For Your sake are we killed all the day long; we are counted as sheep for the slaughter.” Let us then hear in this Psalm the voice of the Martyrs; and see how good is the cause which the voice of the Martyrs pleads, saying, For Your sake, etc....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)