The Israelites wanted a king of their own. They were tired of having judges while their neighbours had kings, so they pressured Samuel to appoint a king for them. So Samuel prayed to God.
And the Lord told him: “Listen to all that the people are saying to you; it is not you they have rejected, but they have rejected me as their king. As they have done from the day I brought them up out of Egypt until this day, forsaking me and serving other gods, so they are doing to you. Now listen to them; but warn them solemnly and let them know what the king who will reign over them will claim as his rights.” 1 Samuel 8:7-9
Even with this warning, the Israelites still insisted on having a king. God sent Samuel to anoint Saul, which he did. God poured His spirit on Saul. Back then, Saul was so humble, he hid himself among the supplies when Samuel came to make him king.
Nahash the Ammonite attacked the city of Jabesh. He agreed to a treaty only he gets to gouge out an eye of everyone in the city. When King Saul heard about this, the spirit of God came upon him. He gathered his men, attacked and slaughtered the Ammonites, saving the city of Jabesh from them. That confirmed his kingship. He was 30 old and reigned over Israel for 42 years.
The Philistines with 3,000 chariots, 6,000 charioteers and soldiers assembled to fight Israel. Saul assembled his men and waited 7 days for Samuel to come to Gilgal, but when the men got impatient and began to scatter, Saul offered the burnt offering to God himself, a holy duty that was meant for Samuel. In doing so, Saul broke God’s command. Hence God sought a man after his own heart and appointed him ruler of his people.
God sent a panic into the whole army of Philistines and Saul and his men found the Philistines totally confusing, striking one another with their swords.
Samuel said to Saul, “I am the one the Lord sent to anoint you king over his people Israel; so listen now to the message from the Lord. This is what the Lord Almighty says: ‘I will punish the Amalekites for what they did to Israel when they waylaid them as they came up from Egypt. Now go, attack the Amalekites and totally destroy all that belongs to them. Do not spare them; put to death men and women, children and infants, cattle and sheep, camels and donkeys.’”
1 Samuel 15:1-3
Saul attacked and defeated the Amalekites, but he spared Agag and the best of the animals, directly disobeying God. God regretted making Saul king. He sent Samuel to confront Saul for his disobedience. Samuel confronted Saul. Saul defended his actions.
But Samuel said to him, “I will not go back with you. You have rejected the word of the Lord, and the Lord has rejected you as king over Israel!” 1 Samuel 15:26
Now the Spirit of the Lord had departed from Saul, and an evil spirit from the Lord tormented him. 1 Samuel 16:14
Saul’s servants found David, who was renown for playin g the lyre beautifully. Saul sent for him. Whenever the evil spirit came on Saul, David would pay the lyre and the evil spirit will leave Saul.
Saul had 3 sons and 2 daughters. His son Jonathan became David’s best friend and his daughter MIchal became David’s wife. David, however was chosen by God to replace Saul as king and in the later part of his life, Saul pursued David with the intention of killing him. God delivered Saul into David’s hands twice and David spared Saul on both occasions.