Because Samuel was a prophet he heard from God. Saul had been the people's choice. God would now give the people His choice "a man after His own heart". Saul was the anointed commander or prince while David will become the anointed king.
Samuel got a command from the Lord to go to Jesse. He had to take with him a horn filled with oil to anoint a son of Jesse. At first Samuel did not want to go because he knew that Saul will go after him if he knows what Samuel was going to do. The full purpose of his journey was not disclosed to Saul. The big difference is "the Lord does not see as man sees for man looks at the outward appearance but the Lord looks at the heart".
The Lord gave Samuel an instruction to show him which son it must be. Then when David arrives Samuel knows that this is the son that must be anointed. Then Samuel anointed him in the midst of his brothers and the Spirit of the Lord came upon David from that day on. David was still young.
The Spirit of the Lord departed from Saul and he was troubled. In the absence of the spirit of the Lord men are vulnerable to evil spirits. When ever you do not submit to God and His rule we are no longer protected from evil and its destructive effects. After David defeated Goliath Saul had a specific strategy in mind after he heard what the woman sung. This made him more distressed because he was under the influence of an evil spirit. Saul strategy was to place David in the major battles with the Philistines in order that he may be killed in battle. Saul also presumed that David will put his own life in jeopardy in order to get married to his daughter.
When nothing happened to David and he married Saul's daughter, Saul became more afraid of David. Saul spoke to his servants and to Jonathan to kill David. Jonathan told David about this plot because of the covenant between them. Saul pursuit David and wanted to destroy him. Saul was jealous because he knew that David found favour and he was popular amongst the people. On two occasions Saul's life was spared by David. This made him angrier.
After his rejection Saul became a tragic figure. He was full of jealousy and fear. When all his plans failed he even turned to superstition. He consulted a medium. This medium and the spiritist were those who deal with spirits of the dead. This practice was totally against the law. He disguised himself in doing so. In his final years he relentless chased David in an effort to kill him. Saul pursuit David for many years but failed to do what he plant to do.
The Philistines fought against Israel and the men of Israel fled. They were after Saul's sons and followed them. Then they killed Jonathan, Abinadad and Malchishua. An archer hit Saul and he was severely wounded. Saul asks his arm bearer to kill him. His arm bearer did not want to do it and was afraid. Saul then took the sword and fell into it killing himself. He committed suicide.
The duty of an arm bearer was to keep the king alive. When he saw what happened he killed himself to. So on this day, Saul three sons, his arm bearer and Saul himself died together.
Finally, Saul who had such a wonderful and promising beginning ends his life in tragedy and suicide. Now the stage was set for David to become the second king of Israel.
What can we learn from this?
Saul was disobedient to God and his commandments. He wants to please the people and that is how he came into power to be the first King of Israel. Saul becomes a tragic figure who cannot succeed to regain what he had. His is driven by jealousy and fear and he gradually loose his sanity. His final years are spent relentlessly chasing David through the wilderness and throughout Israel and his kingdom in an effort to kill him. Disobedience and sin in Saul's life became his downfall.
The tragic death of Saul illustrates the ultimate result of an earthly kingdom. The only hope is a kingdom of God on earth whose ruler is God himself. With David as the next appointed king of Israel the earthly linkage of God's King begins. In Christ, God came and He will come again, as the King of Kings.
Spiritual leadership differs radically from the worlds ideas about how to lead. God leaders must realize that they represent Him in their role since He has given them the authority. In order to honour God His servants must be faithful both to Him and His people.
Spiritual leadership is a sacred trust. The way how Christian leaders conduct themselves impacts far more than their own lives. This is why they will be severely judged (James 3:1). Godly leaders should grow and become stronger through its transmission to subsequent generations.