12 Thus Abraham pleased God, who, that he might please God, did not shrink even from losing his son, or from doing an act of parricide. You, who cannot endure to lose your son by the law and lot of mortality, what would you do if you were bidden to slay your son? The fear and faith of God ought to make you prepared for everything, although it should be the loss of private estate, although the constant and cruel harassment of your limbs by agonizing disorders, although the deadly and mournful wrench from wife, from children, from departing dear ones; Let not these things be offenses to you, but battles: nor let them weaken nor break the Christian's faith, but rather show forth his strength in the struggle, since all the injury inflicted by present troubles is to be despised in the assurance of future blessings.
Unless the battle has preceded, there cannot be a victory: when there shall have been, in the onset of battle, the victory, then also the crown is given to the victors. For the helmsman is recognised in the tempest; in the warfare the soldier is proved. It is a wanton display when there is no danger. Struggle in adversity is the trial of the truth. The tree which is deeply founded in its root is not moved by the onset of winds, and the ship which is compacted of solid timbers is beaten by the waves and is not shattered; and when the threshing-floor brings out the grain, the strong and robust grains despise the winds, while the empty chaff is carried away by the blast that falls upon it.
Source: The Treatises of Cyprian (New Advent)