2 These things we suffer by our own fault and our own deserving, even as the divine judgment has forewarned us, saying, “If they forsake my law and walk not in my judgments, if they profane my statutes and keep not my commandments, then will I visit their transgressions with the rod, and their iniquities with stripes.” It is for this reason that we feel the rods and the stripes, because we neither please God with good deeds nor atone for our sins. Let us of our inmost heart and of our entire mind ask for God's mercy, because He Himself also adds, saying, “Nevertheless my loving-kindness will I not scatter away from them.” Let us ask, and we shall receive; and if there be delay and tardiness in our receiving, since we have grievously offended, let us knock, because “to him that knocks also it shall be opened,” if only our prayers, our groanings, and our tears, knock at the door; and with these we must be urgent and persevering, even although prayer be offered with one mind.
Source: The Epistles of Cyprian (New Advent)