David plays for his King
David's playing on his Harp was the only thing that would settle King Saul's troubled mind.
An evil spirit from God came upon King Saul, David would take his harp and play and King Saul would feel better, and the evil spirit would leave him.
David was an accomplished musician. He practiced many hours while looking after his father's sheep.
David in Saul's service
14 Now the Spirit of the LORD had departed from Saul, and an evil spirit from the LORD tormented him.
15 Saul's attendants said to him, "See, an evil spirit from God is tormenting you. 16 Let our lord command his servants here to search for someone who can play the harp. He will play when the evil spirit from God comes upon you, and you will feel better."
17 So Saul said to his attendants, "Find someone who plays well and bring him to me."
18 One of the servants answered, "I have seen a son of Jesse of Bethlehem who knows how to play the harp. He is a brave man and a warrior. He speaks well and is a fine-looking man. And the LORD is with him."
19 Then Saul sent messengers to Jesse and said, "Send me your son David, who is with the sheep." 20 So Jesse took a donkey loaded with bread, a skin of wine and a young goat and sent them with his son David to Saul.
21 David came to Saul and entered his service. Saul liked him very much, and David became one of his armor-bearers. 22Then Saul sent word to Jesse, saying, "Allow David to remain in my service, for I am pleased with him."
23 Whenever the spirit from God came upon Saul, David
would take his harp and play. Then relief would come to Saul; he would
feel better, and the evil spirit would leave him.
1st Samuel 16:14-23