King Saul attacked his enemies, the Philistines, but the Israelite army was outnumbered and had almost no weapons, so they ran and hid. Saul tried making a burnt offering so God would help him. But then Samuel told him that was a foolish thing to do, and now God had rejected Saul and would have to find a new king for his people.
Later, Samuel told King Saul that God wanted him to break God’s law and kill all the people and animals in the city of Amalek for the sins of their ancestors. So Saul ambushed the city and killed all the people except the king of the Amalekites,1 and all the animals except the best ones, which his men were planning to sacrifice to God later. Then God realized that he had made a bad decision when he made Saul king. Because Saul had failed to kill everyone and everything immediately,2 God rejected Saul as king of his people. Again.
Samuel killed the Amalekite king himself, and then went to Bethlehem to find a new king for Israel from among the sons of Ruth’s grandson Jesse, a family that was not friendly to those who were zealous for God. God told Samuel to lie about why he was going there, so Saul wouldn’t find out and kill him.
Samuel thought Jesse’s oldest son Eliab would make a good king, because he was tall and handsome like the current king that God didn’t like, but God said he had not chosen Eliab to be king. God claimed that he judges potential kings by their character, not their appearance. So then God chose another handsome son of Jesse to be the new king of Israel: David, who would go on to do way more evil than Saul ever had.
But despite being rejected by God twice, Saul remained king of Israel for the rest of his life. David was hired to be King Saul’s armor-bearer, and to play the lyre to comfort Saul whenever God sent evil spirits to torment him.
The moral of the story
Never make sacrifices to God, or God will abandon you, torment you, and kill you.