20 “Turn not away Your face from Your child”. And this is a commending of humility; “from Your child,” that is, “from Your little one:” because now I have been rid of pride through the discipline of tribulation, “turn not away Your face from Your child.” This is that beautiful mercy of God, whereof he spoke above. For in the following verse he explains that whereof he spoke: “For I am troubled, speedily hearken unto me.” What is “speedily”? Now there is no cause why You must defer it: I am troubled, my affliction has gone before; let Your mercy follow.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)