David first came to the court of Saul to play the harp to soothe him when the evil spirit came upon him (1 Samuel 16:15-21). When Saul realized that David was popular with the people and accomplished in war, he feared his rise to power and assualted him with a spear in his tent (1 Samuel 18:5-11). David escaped and Jonathan Saul's son brought peace between them. Again the evil spirit came upon Saul while David played the harp, and Saul tried to pin David to the wall with a spear. David fled from Saul's presence and lived in the desert with men who believed in him.
David taunted Saul by cutting off the hem of his robe without him knowing. David did not cause harm to Saul, but he wanted him to know that he could have (1 Samuel 24:5). Then he was conscience striken because he had humiliated him, and he refused to allow his men to attack. David said, ‘I will not lift my hand against my master, because he is the LORD’s anointed.’
David spared Saul's life a second time when he refused to kill him during a raid on his camp, again saying, "I would not lay a hand on the Lord's annointed." (1 Samuel 22:23)
Saul attempted to take David's life twice and twice David refused to take Saul's. When Saul died in battle, David executed the man who brought the news because he rejoiced over the death of Saul. David mourned for him and honored him in.
This seems like a strange paradox. Saul was mad, perhaps in the girp of a psychotic depression. He was powerful, and David was only acting in self defense. David was committed to Saul, not necessarily because he was the king or even because he was his friend's father or because he was his father in law, but because he was God's chosen man. He honored Saul as his master and as God's annointed. He would not hasten Saul's death even though he knew God had called him to be king. He fled and lived in fear and torment in the desert. God tested David during this time, but he never deserted him.
Even when Saul failed, David did not doubt God's promise or provision. Can we be so faithful to God during a time of testing? Have we secured our promise to God with cords of love and obedience so that human failures do not disturb our peace with Him?