10 “Make me to hear in the morning Your mercy, for in You have I hoped”. Behold, I am in the night, yet “in You have I hoped,” until the iniquity of the night pass away. “For we have,” as Peter says, “a more sure word of prophecy, whereunto ye do well that you take heed, as unto a light that shines in a dark place, until the day dawn, and the daystar arise in your hearts.” “Morning” then he calls the time after the end of the world, when we shall see what in this world we believe.
But what here, until the morning come? For it is not enough to hope for the morning; we must do somewhat. Why do somewhat? God is to be sought with the hands in the night. What is, “with the hands”? By good works. Since then we must thus hope for the morning, and bear this night, and persevere in this patience until the day dawn, what meanwhile must we do here? Lest perchance thou think that you will do anything of yourself, whereby you may earn to be brought to the morning. “Make known to me, O Lord, the way wherein I must walk.”
Therefore did He kindle the lamp of prophecy, therefore did He send the Lord in the vessel, as it were, of the flesh, who should even say, “My strength is dried up like a potsherd.” Walk by prophecy, walk by the lamp of future things predicted, walk by the word of God....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)