1 Samuel 16:19-23

So Saul sent messengers to Jesse to say, “Send me your son David, who is with the flock.”

And Jesse took a donkey loaded with bread and a jug of wine, and he took a young goat, and sent them to Saul by his son David.

Then David came to Saul and attended him; and Saul greatly loved him, and he became his armor bearer.

So Saul sent word to Jesse, saying, “Let David now be my attendant for he has found favor in my sight.”

So it came about whenever the evil spirit from God came to Saul, David would take the harp and play it with his hand; and Saul would feel relieved and become well, and the evil spirit would leave him.