And it came to pass, when the evil spirit from God was upon Saul, that David took a harp, and played with his hand: so Saul was refreshed, and was well, and the evil spirit departed from him.
All Commentaries on 1 Samuel 16:23 Go To 1 Samuel 16
Gregory The Dialogist
AD 604
Indeed, we should not disregard the fact that whenever the evil spirit possessed Saul, David took his harp and soothed his madness. What is symbolized by Saul but the pride of the mighty and what by David but the lowly life of the saints? As often, therefore, as Saul was possessed by the unclean spirit, his madness was soothed by David’s singing. So, too, whenever the disposition of people in power is turned to raving anger by pride, it is proper that we should recall them to a healthy frame of mind by gentle words, sweet tones of the harp, as it were.