The Lord forbid that I should do such a thing to my master

1 Samuel 24:1-22
Afterward, David was conscience-stricken for having cut off a corner of his robe. He said to his men, “The Lord forbid that I should do such a thing to my master, the Lord’s anointed, or lay my hand on him; for he is the anointed of the Lord.” With these words David sharply rebuked his men and did not allow them to attack Saul. And Saul left the cave and went his way.
When David finished saying this, Saul asked, “Is that your voice, David my son?” And he wept aloud. “You are more righteous than I,” he said. “You have treated me well, but I have treated you badly.
May the Lord reward you well for the way you treated me today. I know that you will surely be king and that the kingdom of Israel will be established in your hands. Now swear to me by the Lord that you will not kill off my descendants or wipe out my name from my father’s family.
In the cave near Engedi Saul is completely at David's mercy. His refusal to take a short-cut to the throne brings the king to his senses. But Saul's word is as changeable as his mood. It is not to be relied on. The Hebrew titles of Psalms 57 and 142 - two prayers for help -connect them with this time.
Why?
You have treated me well, but I have treated you badly. David followed God's way, so David had the heart of Jesus and the Lord.
To the servants of the Lord now in churches. Even we don't agree our elders or ministers we should honor the anointed servants. Even away from this Church.
David is King for Saul couldn't kill David, even Saul is a king .  Saul is passive king.
David gave the right of judgement to the Lord.
How?
Treat everyone well, instead of treat others badly, for God has treated me with mercy and Grace.