15 But it might occur to one; if because of sins man was held by the devil, have sins pleased Christ, who saved the needy man from the mighty? Far be it. But “He it is that shall spare the helpless and poor man”: that is, shall remit sins to the man, humble and not trusting in his own merits, or hoping for salvation because of his own virtue, but needing the grace of his Saviour. But when he has added, “and the souls of the poor He shall save:” he has recommended to our notice both the aids of grace; both that which is for the remission of sins, when he says, “He shall spare the poor and needy man;” and that which does consist in the imparting of righteousness, when he has added, “and the souls of the poor He shall save.” For no one is meet of himself for salvation (which salvation is perfect righteousness), unless God's grace aid: because the fullness of the law is nought but love, which does not exist in us of ourselves, but is shed abroad in our hearts through the Holy Spirit which has been given unto us.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)