18 “And against Me they rejoiced, and gathered themselves together”, against Me only: they rejoicing, I sorrowful. But we heard just now in the Gospel, “Blessed are they that mourn.” If they are blessed that mourn, miserable are they that laugh. “Against Me they rejoiced, and gathered themselves together: scourges were gathered together against Me, and they knew not.” Because they laid to My charge things that I knew not, they also knew not Whom they charged.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)