1st Samuel 8 to 1st Samuel 16:13
When Samuel was very old, he made his sons judges, with himself, over Israel. But his sons took bribes, and did other things that they ought not to have done. The people of Israel became so unhappy that they came to Samuel and asked him to give them a king in place of him and his sons.
Samuel was grieved at this request, he prayed to God to know what he should do. God was displeased with the people for wishing to be governed by a king, like other nations, when He Himself was their king. God told Samuel whom he should choose. This was Saul, the son of Kish, a man of the tribe of Benjamin.
Samuel anointed Saul King over Israel and when he was brought before them, all the people shouted, "God save the king!"
At first Saul was a good king, and did all that God commanded him. But he soon became disobedient; and as he turned away from God. For this God decided that a worthy king would be chosen after him and succeed to the throne in place of Saul's children.
God told Samuel to take a horn of oil, and go to Jesse, an Israelite who lived at Bethlehem, and anoint one of his sons, whom He would point out to him to be the future king over Israel.
Samuel was afraid of doing this because he thought that if Saul were to find out he would put him to death. God told him go and offer a sacrifice at Bethlehem, and He would show him what to do.
Samuel went and called the chief men of the town, together with Jesse and his family, to the sacrifice. Jesse made his sons pass before Samuel. When he saw the eldest son, Eliab, a tall, fine-looking man, he thought he must be the one whom God would choose to be anointed king. God said He would not have Eliab because He looked at the heart of man, not at his outward appearance. Seven of Jesse's sons one after another, came before Samuel, none of them were chosen by God.
Samuel asked if all Jesse's children were there. Jesse answered he had one more son, David, the youngest, who was away keeping sheep. Jesse sent for David. He was a handsome youth. As soon as he came, God told Samuel to anoint him because he was the one whom He had chosen.
Samuel anointed David king. The Spirit of God then came upon David, and remained with him from that day.