"How long will you mourn for Saul,
since I have rejected him as king over Israel?"
–1 Samuel 16:1
Saul has been rejected as king over Israel by God for his disobedience in the Amalekite affair. God had instructed Saul to "totally destroy everything" of the Amalekites but Saul reserved the more desirable sheep and cattle for his army. A more egregious action was to spare the life of Agag, the Amalekite king. Saul had transported his spoils back to Gilgal after first erecting a monument to himself in Carmel. It was in Gilgal, the place of Saul's inauguration where Samuel confronted Saul and informed him of God's rejection. After killing king Agag himself, Samuel would not see Saul again.
Why did the Amalekites incur God's wrath? Because they were antagonistic to Israel from the time they left Egypt. The Amalekites were descendants of Esau (Genesis 36:12) and the sibling rivalry that manifested between Jacob and his brother apparently never improved.
The most interesting point is not that God punished Amalek's descendants but that he did so four hundred years after they gave him a reason to. In a world that places a premium on instant gratification, it is important to remember that God has a plan that will be realized on his schedule.
1Samuel 16:1 The Lord said to Samuel, "How long will you mourn for Saul, since I have rejected him as king over Israel? Fill your horn with oil and be on your way; I am sending you to Jesse of Bethlehem. I have chosen one of his sons to be king."
Samuel loved Saul and Saul's failure weighed heavy on him. God had rejected Saul as king and now has a task for Samuel; he is to travel the ten miles to Bethlehem and anoint one of Jesse's sons to be king in Israel. Samuel will have to pass through Saul's home town of Gibeah and is concerned Saul will kill him. God instructs Samuel to take a heifer with him and say that he is on his way to sacrifice to the Lord. Samuel's concern for his life indicates Saul's state of mind. Saul knows he has been rejected by God, but like many powerful men, he is intent on retaining his position. He will devolve to a state of jealous madness.
When Samuel arrives in Bethlehem, the elders are wary of his presence but he puts them at ease and instructs them to consecrate* themselves and join him at the sacrifice. Samuel consecrates Jesse and his sons and invites them to the sacrifice. Samuel is impressed with Jesse's oldest son, Eliab but God rejects him.
1Samuel 16:7 But the Lord said to Samuel, "Do not consider his appearance or his height, for I have rejected him. The Lord does not look at the things man looks at. Man looks at the outward appearance, but the Lord looks at the heart."
Samuel calls for the second son, Abinadab and then the third, Shammah; altogether seven, but God rejected all of them. Samuel asks Jesse if this is all of his sons and Jesse tells him of the youngest out tending the sheep. The young shepherd is brought before Samuel and God directs Samuel to anoint him; "he is the one."
1Samuel 16:13 So Samuel took the horn of oil and anointed him in the presence of his brothers, and from that day on the Spirit of the Lord came upon David in power. Samuel then went to Ramah.
This anointing of David probably took place around 1025 B.C. and David would have been about fifteen years old. Saul had been anointed in 1050 B.C. when he was thirty years old, so this would make him fifty-five when God chose David. It is important to note that this anointing had witnesses. Samuel had anointed Saul privately in Ramah; David's ceremony was small, but done in front of his family and the elders of Bethlehem. This would be important testimony in the future to prove David's ambitions were not politically selfish.
Consider also that when David and Saul were anointed by Samuel, it was similar to the act of receiving the Holy Spirit. On one hand, nothing seemed to change; Saul went back to plowing with his oxen, David quite likely had to go back and tend the sheep - he was still the youngest and still living with his father and brothers. On the other hand, everything changed; they both were set apart by God for service to God. They were fundamentally different people.
*Consecrate Basically it means to cleanse yourself physically and mentally in preparation for the service of God. The Hebrews were to wash themselves and put on clean clothes. Read Leviticus, chapter 15 for the gory details.
1Samuel 16:14 Now the Spirit of the Lord had departed from Saul, and an evil spirit from the Lord tormented him.
When David was anointed, the "Spirit of the Lord came upon David in power." About that same time, the same Spirit that Saul had enjoyed left him and was replaced by a tormenting entity. Saul's servants, in an attempt to ease his despondency, suggested finding a musician to play for the king and maybe lift his spirit. Saul agrees and one of the servants remembered the son of Jesse who knew how to play the harp.
David presence is requested by the king and Jesse loads provisions on a donkey and sends his son to Saul. Saul was well pleased with David and made him one of his armor-bearers. Whenever the "evil spirit" from God came upon Saul, David would play his harp and Saul would have relief. In short, David was a house musician.
The Place: The Valley of Elah is about fifteen miles west of Bethlehem and runs from east to west. The camp of the Philistines is between Azekah and Socoh on the east end of the valley. Presuming the Philistines occupied the hill closest to camp, they would have been on the south-east end of the valley. The Israelites would be on the hillside to the north. The valley is around a mile wide with a stream running through it. Goliath's home is Gath about five miles to the west. All of this is on the border between Judah and Philistia.
The Champion: Goliath is described as a champion of the Philistines standing nine feet tall. (Hebrew text says, "six cubits and a span." That is about three meters which is more than nine feet.) His armor weighs one hundred twenty-five pounds. He wore bronze shin-greaves, a bronze javelin, and had a spear with the shaft of a weaver's beam and a fifteen pound iron point. (I looked these things up, there is considerable dispute over the size of a weaver's beam and what a shekel of iron weighed, but it's safe to say it was big and heavy, like the guy throwing it.) The end of verse 7 says, "His shield bearer went ahead of him.", you know, in case it was dangerous.
The Challenge: The ancient Greeks were related to the Philistines. In the Greek (and Philistine) tradition, there was the concept of "trial by combat" –a kind of "drawing of lots" where the victory of one warrior over another would be taken as a judgment by God over which side should be victorious. For forty days, morning and evening, Goliath would go to the front lines and call out for the Israelites to send an opponent to fight him; if Goliath was defeated and killed, the Philistines would be Israel's subjects but if Goliath was victorious, Israel would serve Philistia.
The Problem: The same as always, Israel had no faith in the covenant promises that God would preserve them. Saul had lost faith in God even before the Amalekites and now, with God's empowering spirit removed, Saul saw no good way to engage the Philistines. Without God, Saul didn't know how to proceed. Remember, Israel was never to fear her enemies, but to trust in the Lord.
Exodus 14:13-14 13. Moses answered the people, "Do not be afraid. Stand firm and you will see the deliverance the Lord will bring you today. The Egyptians you see today you will never see again. 14. The Lord will fight for you; you need only to be still."
Numbers 14:9 Only do not rebel against the Lord . And do not be afraid of the people of the land, because we will swallow them up. Their protection is gone, but the Lord is with us. Do not be afraid of them."
Enter David: David had been brought into service for Saul as an armor-bearer and house musician but he was still traveling home to help his father with the sheep. His three older brothers were serving in Israel's army under Saul and were at the war-front in the Valley of Elah. Jesse, David's father, directed David to delivers some bread, grain, and cheese to his brothers and bring back news of their condition. David arrived just as the two armies were taking up position as they did each day. David rushes out to greet his brothers and was talking to them when Goliath came out and made his usual boast.
David witnessed the reaction of the Israelites; the running in fear and the general terror. He also overheard the people talking about the reward the king would bestow on anyone who would kill the giant, the fact that Saul would give his daughter to the victor. David was asking about the reward when Eliab, his oldest brother, started giving him a hard time. David was taken to Saul because of the things he was saying and when he stood before the king, David said that he would fight the giant.
The bible doesn't say for sure how old David was when he fought Goliath, but we know he wasn't twenty years old yet. Numbers 1:3 indicates you needed to be twenty to fight in Israel's army and Saul initially told David he would not be able to fight because he was only a boy. David is persistent, though:
1Samuel 17:34-37 34. But David said to Saul, "Your servant has been keeping his father's sheep. When a lion or a bear came and carried off a sheep from the flock, 35. I went after it, struck it and rescued the sheep from its mouth. When it turned on me, I seized it by its hair, struck it and killed it. 36. Your servant has killed both the lion and the bear; this uncircumcised Philistine will be like one of them, because he has defied the armies of the living God. 37. The Lord who delivered me from the paw of the lion and the paw of the bear will deliver me from the hand of this Philistine." Saul said to David, "Go, and the Lord be with you."
Saul gives David his own tunic and they bring out armor and a helmet and a sword, but the gear is awkward and David takes it off. He collects five smooth stones from the stream, puts them in his pouch and with his staff in one hand and his sling in the other, he approaches the Philistine. The staff is symbolically appropriate. David is the newly appointed shepherd of God's people, approaching overwhelming danger with every confidence that God has his back. As he approaches the Philistine, Goliath also recognizes David as "just a boy" and despises him for it.
1Samuel 17:43-47 43. He said to David, "Am I a dog, that you come at me with sticks?" And the Philistine cursed David by his gods. 44. "Come here," he said, "and I'll give your flesh to the birds of the air and the beasts of the field!" 45. David said to the Philistine, "You come against me with sword and spear and javelin, but I come against you in the name of the Lord Almighty, the God of the armies of Israel, whom you have defied. 46. This day the Lord will hand you over to me, and I'll strike you down and cut off your head. Today I will give the carcasses of the Philistine army to the birds of the air and the beasts of the earth, and the whole world will know that there is a God in Israel. 47. All those gathered here will know that it is not by sword or spear that the Lord saves; for the battle is the Lord 's, and he will give all of you into our hands."
With that, Goliath moves against David, but David brings down the giant with his first stone - it sinks into Goliath's forehead - and he goes over and picks up Goliath's sword and cuts off the Philistine's head. You can almost hear the hush of the crowd by just reading that.
The results were predictable. The Philistines turned and ran back to Ekron and Gath with the Israelites pursuing and killing them along the way. I suppose they forgot about Goliath's deal of subjecting themselves to Israel. When the battle subsided, the Hebrews plundered the Philistine camp at the edge of the valley. David kept Goliath's sword and his head as a trophy.
It's interesting to note, that Saul wasn't sure who David was. Chapter sixteen, verse twenty-one indicates that Saul liked David and wanted Jesse to allow him to remain in service, but it seems likely that David had just become a "face in the crowd" to Saul. The last few verses of chapter seventeen indicate that Saul wanted Abner, his army commander, to find out who David's father was. Abner brought David to Saul - still holding Goliath's head - and Saul asked him who his father was.