7 He then begins to prophesy what they should receive for this very impiety; detailing their lot in such a manner, as if he wished its realization from a desire of revenge. Some not understanding this mode of predicting the future, under the appearance of wishing evil, suppose hatred to be returned for hatred, and an evil will for an evil will, since in truth it belongs to few to distinguish, in what way the punishment of the wicked pleases the accuser, who longs to satiate his enmity; and in how widely different a way it pleases the judge, who with a righteous mind punishes sins. For the former returns evil for evil: but the judge when he punishes does not return evil for evil, since he returns justice to the unjust; and what is just, is surely good. He therefore punishes not from delight in another's misery, which is evil for evil: but from love of justice, which is good for evil....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)