1 Samuel 26:9

But this is marvelous not only for the fact that he grants life to the one who is doing everything against his life, but because David, although he had been anointed to the office of king and knew that he would not otherwise partake of that position unless Saul were out of the way, judged it better to suffer ill patiently in his private low estate than to enter upon the kingship by satisfying his anger against the one who had caused him grief.

For who has stretched out his hand against the Lord's anointed? etc., according to the ongoing exposition indeed demonstrates that no one is free from the crime of sacrilege, who attempts to invade the kingdom of the Jewish people, given specially to him by the Lord, and consecrated with holy oil, and to profane the city and the temple dedicated to divine worship, disregarding the fear of God. But according to the supplicant's sense of the statement, it teaches with what great reverence divine sacraments must be treated, even though they are dispensed by the hands of the wicked; how much honor is due to persons devoted to the service of the sacred altar, how much presumption should be restrained from harming these persons, no matter how wickedly they live, because of the mark of any rank, since he himself, the exile, innocent, refrained from killing the most unjust persecutor of him, solely because of the holy oil of anointing which he had received in the figure of Christ either of the name or of the kingdom which he was not to preserve, and restrained his soldier by command and himself by divine fear. Therefore, we must be careful not to presume to defame and attack the reputation of bishops, presbyters, deacons indiscriminately.

After that, the opportunity to kill the enemy presented itself to him twice. Once in the cave Saul fell into David's hands unawares, and again in the tent when he was relaxed in sleep. David stood over him when he was asleep, and when he could have satisfied all his anger by murdering the one who pursued him, he did not lay a hand on him himself, and he said to the one eager for the kill, "Do not destroy." The voice which prevents destruction in the case of this man is obviously the voice of God.For this reason, just as those who produce the more notable inscriptions on stones cut the characters deeply by frequently applying the chisel with blows to the carving of the letters, so the Holy Spirit contrives, by means of continuous repetition, that this great saying may become more distinct and quite clear on the stela of our memory, so that this inscription, having been carved in us distinctly and without confusion, might be known well in the time of misfortunes. For, in my opinion, the goal of the economy of the Holy Spirit is to set forth the previous accomplishments of holy ones for guidance for the life after these accomplishments, the representation leading us forward to good which is equal and similar. For whenever the soul swells with revenge against someone who is provoking it, and the blood around the heart boils with anger against the one who has grieved the soul, then, when one has looked up at this stela which the Holy Spirit set up for David, and has read the word on it which David uttered on behalf of him who was eager for his own blood, he will not fail to calm the troubled thoughts in his soul and appease his passion by his desire to imitate the same things.