18 One of the young men spoke up, "I know someone. I've seen him myself: the son of Jesse of Bethlehem, an excellent musician. He's also courageous, of age, well-spoken, and good-looking. And God is with him." 19 So Saul sent messengers to Jesse requesting, "Send your son David to me, the one who tends the sheep." 20 Jesse took a donkey, loaded it with a couple of loaves of bread, a flask of wine, and a young goat, and sent his son David with it to Saul. 21 David came to Saul and stood before him. Saul liked him immediately and made him his right-hand man. 22 Saul sent word back to Jesse: "Thank you. David will stay here. He's just the one I was looking for. I'm very impressed by him." 23 After that, whenever the bad depression from God tormented Saul, David got out his harp and played. That would calm Saul down, and he would feel better as the moodiness lifted.
Matthew Henry's Commentary on 1 Samuel 16:18-23
Commentary on 1 Samuel 16:14-23
(Read 1 Samuel 16:14-23)
Saul is made a terror to himself. The Spirit of the Lord departed from him. If God and his grace do not rule us, sin and Satan will have possession of us. The devil, by the Divine permission, troubled and terrified Saul, by the corrupt humours of his body, and passions of his mind. He grew fretful, peevish, and discontented, and at times a madman. It is a pity that music, which may be serviceable to the good temper of the mind, should ever be abused, to support vanity and luxury, and made an occasion of drawing the heart from God and serious things. That is driving away the good Spirit, not the evil spirit. Music, diversions, company, or business, have for a time often been employed to quiet the wounded conscience; but nothing can effect a real cure but the blood of Christ, applied in faith, and the sanctifying Spirit sealing the pardon, by his holy comforts. All other plans to dispel religious melancholy are sure to add to distress, either in this world or the next.