2 Samuel 12:4

And with what moderation and self-restraint those men used their wives appears chiefly in this, that when this same king, carried away by the heat of passion and by temporal prosperity, had taken unlawful possession of one woman, whose husband also he ordered to be put to death, he was accused of his crime by a prophet, who, when he had come to show him his sin, set before him the parable of the poor man who had but one ewe lamb, and whose neighbor, though he had many, yet when a guest came to him, refused to take of his own flock but set his poor neighbor's one lamb before his guest to eat. And David's anger being kindled against the man, he commanded that he should be put to death and the lamb restored fourfold to the poor man; thus unwittingly condemning the sin he had wittingly committed. And when he had been shown this, and God's punishment had been announced against him, he wiped out his sin in deep penitence. But yet in this parable it was the adultery only that was indicated by the poor man's ewe lamb. About the killing of the woman's husband—that is, about the murder of the poor man himself who had the one ewe lamb—nothing is said in the parable, so that the sentence of condemnation is pronounced against the adultery alone. And hence we may understand with what temperance he possessed a number of wives when he was forced to punish himself for transgressing in regard to one woman. But in his case the immoderate desire did not take up its abode with him but was only a passing guest. On this account the unlawful appetite is called even by the accusing prophet, a guest. For he did not say that he took the poor man's ewe lamb to make a feast for his king, but for his guest. In the case of his son Solomon, however, this lust did not come and pass away like a guest but reigned as a king. […]

For I admit my wrongdoing, and my offense confronts me all the time. "I have not thrust my deed behind my back; I do not look askance at others while forgetting myself; I do not presume to extract a speck of straw from my brother's eye while there is a timber in my own; my sin is in front of me, not behind my back. It was behind me until the prophet was sent to me and put to me the parable of the poor man's sheep." What the prophet Nathan said to David was this: There was a certain rich man who had a large flock of sheep. His neighbor was a poor man who had only one little ewe lamb; she rested in his arms and was fed from his own dish. Then a guest arrived at the rich man's house. The rich man took nothing from his flock; what he wanted was the little ewe lamb that belonged to his neighbor, so he slaughtered that for his guest. What does he deserve? Angrily David pronounced sentence. Obviously the king was unaware of the trap into which he had fallen, and he decreed that the rich man deserved to die and must make fourfold restitution for the sheep. It was a very severe view, and entirely just. But his own sin was not yet before his eyes; what he had done was still behind his back. He did not yet admit his own iniquity and hence would not remit another's. But the prophet had been sent to him for this purpose. He brought the sin out from behind David's back and held it before his eyes, so that he might see that the severe sentence had been passed on himself. To cut away diseased tissue in David's heart and heal the wound there, Nathan used David's tongue as a knife.

Therefore, Nathan went to David and wove a dramatic act for judgment. And what did he say? "My king, I want your judgment. There was a certain rich man and a certain poor one. The rich person possessed herds of cattle and many other flocks; and the poor one had one ewe that drank from his glass, ate from his table and slept in his embrace." Here Nathan revealed the genuine bond between a husband and wife. "When a certain stranger arrived, the rich man desired to keep his own animals, and he took the poor man's ewe and slaughtered her." Here, do you see how Nathan wove the dramatic act, mysteriously concealing the weapon in the glands of David's throat? Then what did the king say? Thinking that he had to pass judgment against someone else, he decided most severely. For such are human beings. When it concerns other people, they gladly and abruptly render decisions and publicize them. And what did David say? "As the Lord lives, the man who did this thing is worthy of death. And he shall restore the lamb fourfold." Therefore, what did Nathan reply? He did not allow the wound to be relieved for many hours; rather, he quickly stripped it naked and sharply embedded the knife deeply into it, so as not to rob it of the painful sensation. "You are the man, my king." What did the king say? "I have sinned against the Lord." He did not say, "Who are you who censures me? Who sent you to speak with such boldness? With what daring did you prevail?" He did not say anything of the sort; rather, he perceived the sin. And what did he say? "I have sinned against the Lord." Therefore, what did Nathan say to him? "And the Lord remitted your sin." You condemned yourself; I [God] remit your sentence. You confessed prudently; you annulled the sin. You appropriated a condemnatory decision against yourself; I repealed the sentence. […]

And there came a traveller unto the rich man,....

Marriage is a remedy against fornication, but marrying many is not; for, when once the law of unity is transgressed, the indulged lust will hardly stint itself.