David and Saul, Again?

The Ziphites went to Saul at Gibeah and said, “Is not David hiding on the hill of Hakilah, which faces Jeshimon?” So Saul went down to the Desert of Ziph, with his three thousand select Israelite troops, to search there for David. Saul made his camp beside the road on the hill of Hakilah facing Jeshimon, but David stayed in the wilderness. When he saw that Saul had followed him there, he sent out scouts and learned that Saul had definitely arrived. Then David set out and went to the place where Saul had camped. He saw where Saul and Abner son of Ner, the commander of the army, had lain down. Saul was lying inside the camp, with the army encamped around him. (1 Samuel 26:1-5 NIV)

This is David's "second encounter" with a Saul who really wants to hunt him down and kill him. One thing I really do not understand is that why did Saul continue to persue David even after his first encounter? We remember him saying:

“You are more righteous than I,” he said. “You have treated me well, but I have treated you badly. You have just now told me about the good you did to me; the Lord delivered me into your hands, but you did not kill me. When a man finds his enemy, does he let him get away unharmed? 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.” (1 Samuel 24:17-21 NIV)

Saul understood and see the point that David is not to be Persued and still continues to persue David? Even he knows that God is with David and Saul would never be able to touch him? Saul was tempted by evil? It was mentioned before that Saul was being tormented by evil spirits and the glory of God left him. People do foolish things to disobey God. Some by doing thing they know they cannot accomplish like Saul. Some borrowed power from satan to accomplish such things. But they all forgot the one most important truth that God is the end, He is the utmost powerful and nothing goes beyond Him. That He is final. But why people like Saul know it but yet disobeyed. Know it yet run away from His will? Praise The Lord for all the things He have done that His glory shall not depart from me. Lord I pray a prayer of wisdom and presence over my life. Of Your wisdom and Your presence. Lord I pray in your glorious name, amen.