2 Samuel 23:17

I do not fear the uncleanness of food but only the uncleanness of uncontrolled desire. I know that Noah was permitted to eat every kind of meat which was edible; that Elijah was nourished on meat; that John, endowed with a marvelous abstinence, was not made unclean by partaking of living things, namely, the locusts which happened to be available as food. And I know that Esau was led into error by his greed for lentils; that David blamed himself for his craving for water; and that our King was tempted not by flesh but by bread. Further, the people in the desert deserved to be reprimanded, not because they desired meat but because they murmured against the Lord as a result of this desire for meat. Having been placed among these temptations, then, I struggle daily against undisciplined desire in eating and drinking.

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?"

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, …

When long afterward David 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.

Fifthly, Thus he would honour God and give glory to him. The water purchased at this rate he thought too precious for his own drinking and fit only to be poured out to God as a drink-offering. If it was the blood of these men, it was God's due, for the blood was always his.