10 Behold, this day thine eyes have seen how that the LORD had delivered thee to day into mine hand in the cave: and some bade me kill thee: but mine eye spared thee; and I said, I will not put forth mine hand against my lord; for he is the LORD's anointed.
[AD 395] Gregory of Nyssa on 1 Samuel 24:8-11
Saul, therefore, came out of the cave unaware of what had happened, wearing the little garment which had been trimmed all around. David came out behind him in self-assurance, and having seized the hill lying above the cave in advance, held out the end [of Saul’s robe] in his hand. This was nothing other than a bloodless trophy against his enemies. And he cried out to Saul in a loud voice and told him about this new and marvelous heroism, which was unstained by the defilement of blood, in which the hero was victorious and the one defeated was saved from death. For David’s excellence is not attested in the fall of his enemy, but the superiority of his power is made clearer in the salvation of his opponent from danger. He had such an excess of confidence that he did not think that his own salvation lay in the destruction of those arrayed against him, but even when those who plotted against him survived he was confident that no one would harm him.But the Word teaches rather by this story that the one who excels in virtue does not fight bravely against those of his own race but fights against the passions. The anger in both men, then, was destroyed by such excellence as David had, in the one, when he destroyed his own wrath by means of reason and quenched the urge to take vengeance, and in the other, when Saul put to death his evil against David because of the clemency which he had experienced. For one can learn from the story itself the kind of things Saul uttered afterwards to the victor when he was submerged in shame for what he had undertaken and demonstrated his spontaneous turning away from evil by his lament and tears.

[AD 407] John Chrysostom on 1 Samuel 24:8-11
When he had offered this excellent sacrifice, then, achieved the victory and omitted nothing needed for a trophy, the cause of the problem, Saul, arose and left the cave, all unaware of what had gone on. “David also left behind him,” looking in the direction of heaven with eyes now free of concern, and more satisfied on that occasion than when he had overthrown Goliath and cut off the savage’s head. It was, in fact, a more conspicuous victory than the former one, the spoils more majestic, the booty more glorious, the trophy more commendable. In the former case he needed a sling, stones and battle line, whereas in this case thought counted for everything, the victory was achieved without weapons, and the trophy was erected without blood being spilt. He returned, therefore, bearing not a savage’s head but resentment mortified and rage unnerved—spoils he deposited not in Jerusalem but in heaven and the city on high.

[AD 407] John Chrysostom on 1 Samuel 24:8-11
So what did David reply? “Your servant, my lord the king.” A contest and rivalry then developed as to which one would pay greater respect to the other: one admitted the other to kinship, the other called him lord. What he means is something like this: I am interested in one thing only, your welfare and the progress of virtue. You called me child, and I love and am fond of you if you have me as a servant, provided you set aside your resentment, provided you do not suspect me of any evil or think me to be scheming and warring against you. He fulfilled that apostolic law, note, that bids us excel ourselves in showing one another honor, unlike the general run of people, whose disposition is worse than beasts’ and who cannot bear to be the first to greet their neighbor, having the view that they are shamed and insulted if they share a mere greeting with someone.