8 “What should I do then?” Hear what you should do. “Submit to the Lord, and entreat Him”. Let this be your life, to obey His commandments. For this is to submit to Him; and to entreat Him until He gives you what He has promised. Let good works “continue;” let prayer “continue.” For “men ought always to pray, and not to faint.” Wherein do you show that you are “submitted to Him”? In doing what He has commanded. But haply thou dost not receive your wages as yet, because as yet you are not able. For He is already able to give them; but you are not already able to receive them. Exercise yourself in works. Labour in the vineyard; at the close of the day crave your wages. “Faithful is He” who brought you into the vineyard. “Submit to the Lord, and entreat Him.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)