Gregory the Great, on 2Sam 23:15

“And David longed, and said: O that some man would get me a drink of the water out of the cistern, that is in Bethlehem, by the gate.”

“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.”

Imported from an open dataset — not yet checked against the printed edition.