2 Samuel 23:15

A fish is caught by being enticed with a hook. A bird falls into a net while trying to get food. Animals that are tough by nature's endowment fall into a pit from desire to eat, and what nature does not soften, food deceives. Therefore, learn temperance and parsimony from the prayer and the examples of ancients: from prayer, because the Lord says, "Lest your hearts be overburdened with self-indulgence and drunkenness"; from examples, because David was unwilling to drink the water he wanted, since he recognized the danger of being responsible for another's blood; and because Daniel scorned the feasts of kings and lived on vegetables. What you possess in common with your companions should be acceptable to you and you should not cause others to be intemperate; also, do not become a cause for scandal to those to whom you wish to set an example by encouragement and by proof of a good life.

And certainly when we are disturbed at this very anger because it has stolen upon us against our brother, and we angrily cast out its deadly suggestions and do not permit it to maintain its noxious lair in the recesses of our heart. To be angry in this latter way is also taught us by that prophet who so eradicated this from his mind that he did not even want to take revenge on his own enemies, who had in fact been handed over to him by God, when he said, "Be angry and do not sin." For when he wanted water from a well in Bethlehem and had been brought it by strong men from the midst of enemy troops, he at once poured it out on the ground and, angrily extinguishing his wanton and passionate desire in this way, he offered it as a libation to the Lord, rejecting his yearning and desire with the words "May the Lord be gracious to me, lest I do this. Shall I drink the blood of those men who went out and the danger of their souls?"

What I say is excessive, unless I confirm these things from testimonies of sacred Scripture. The Law of the Old Testament certainly forbids coveting another's wife, but it does not punish a king for commanding brave deeds of soldiers, or for desiring water. And we all know that David, pierced by the sword of concupiscence, both coveted and took away another man's wife. Fitting scourges followed his fault, and he corrected the evil he had perpetrated through the lamentations of penance. When long afterward he sat against the battle lines of enemies, he wished from desire to drink water from the cistern of Bethlehem. His chosen soldiers, breaking through the midst of the opposing forces, brought back unharmed the water the king had desired. But the man instructed by scourges immediately reproached himself for having desired water at the peril of his soldiers, and pouring it out, he offered it to the Lord, as it is written there: He poured it out to the Lord. For the water poured out was turned into a sacrifice to the Lord, because he slew the fault of concupiscence through the penance of his self-reproach. He therefore who once did not at all fear to covet another's wife, afterward was even afraid because he had coveted water. For since he remembered having perpetrated unlawful things, now stern against himself, he abstained even from lawful things. Thus, thus do we do penance, if we perfectly bewail what we have committed.