Well ok, you keep asking for it.
We can start with the reworked versions of Samuel, David and Goliath hoping to achieve their goal of converting the ordinary Israeli people into a "miraculous people."
"Saul had an evil spirit tormenting him 'sent by God'. (1 Samuel 16:14)
Someone recommended David to play the harp, calling him,
"a brave warrior, a mighty man of war." (1 Samuel 16:18) . "David came to Saul and entered his service."
(1 Samuel 16:21)
Saul took a liking to David and told his father,
"'allow David to enter my service,' for, 'he loved him dearly.' " (1 Samuel 16:21)
The second version of their meeting is found at the end of 1 Samuel Chapter 17 . David spoke of killing Goliath, and his words were reported to Saul. (1 Samuel 17:31) Saul did not want to let David fight Goliath, for David was not a trained warrior. David was just a lad and out tending sheep, and his job was to deliver lunch to the soldiers. (1 Samuel 17:18)
"You are not able to go to war against the Philistines. You (David) are just a boy, and Goliath is a man of war."
(1 Samuel 17:33)
Saul relented, and
"clothed David with his armor and said, 'go! May God be with you.'" (1 Samuel 17:37)
David killed Goliath. David took Goliath's head to Jerusalem, but he kept his sword in his tent. (1 Samuel 17:54) Jerusalem was not captured from the Jebusites until after David became King (or was it?) and the sword we are told (in another variant) was kept in a temple at Nob. (1 Samuel 21:1) No sooner had David cut off Goliath's head than Saul asked,
"who is that young man?" (1 Samuel 17:55)
David was introduced to Saul
"with the Philistines head still in his hand,"
(1 Samuel 17:57)
and Saul asked,
"who are you?" and David replied, "the son of Jesse."
(1 Samuel 17:58) "That same day Saul kept David and would not let him return to his father's house."
(1 Samuel 18:1)
Rather than a harp player the young adolescent boy was made
"commander of the fighting forces," (1 Samuel 18:5)
an act which pleased everyone, including Saul and his officials.
A few verses later an editorial comment is inserted in a futile attempt to harmonize the compounding contradictions and multiple inconsistencies.
"David played the harp for Saul, as he had done before," (1 Samuel 18:10)
for an evil spirit was tormenting Saul. In this variant David was removed from Saul's household and
"made a commander" (1 Samuel 18:13) because, "Saul was afraid of David for he saw that God was with him." (1 Samuel 18:12)
Note that David was living at home and tending sheep just before killing Goliath, and was not living with Saul, and 'playing the harp for him as he did before', as this weak editorial excuse would try to suggest. When David killed Goliath, they do not know each other. 'That same day' David entered the service of Saul. It then follows that David could not have 'played the harp for Saul, as he did before.' The comment was inserted by an editor well aware of the inconsistencies between the two stories, in a futile attempt to reconcile the multiple versions of events and fuse them into one (pseudo- consistent) manuscript.
Also note that another editorial comment was included
for the same purpose.
"David occasionally left Saul's house (where he was the resident harp player) to feed his father's sheep in Bethlehem." (1 Samuel 17:15)
This futile excuse is intended to explain why David was not 'living with Saul' and 'playing the harp for him as before' but rather living at home with his father and tending sheep just before killing Goliath.
Note that David is both a 'skilled warrior' and 'a young boy, untrained for war.' David is both 'living at home' and 'living with Saul'. Saul knows David, as his personal harp player, even outfitting him to battle Goliath. Saul does not know who David is, and must be introduced to David after he kills Goliath ("who is that young man?') David enters Saul's service as a harp player, and as 'commander of the fighting forces', on two different occasions."
Source
http://www.awitness.org/contrabib/history/jebusite.html