1 Samuel 29:6 (KJV)

And the princes of the Philistines were wroth with him; and the princes of the Philistines said unto him, Make this fellow return, that he may go again to his place which thou hast appointed him, and let him not go down with us to battle, lest in the battle he be an adversary to us: for wherewith should he reconcile himself unto his master? should it not be with the heads of these men?

Is not this David, of whom they sang one to another in dances, saying, Saul slew his thousands, and David his ten thousands?

Then Achish called David, and said unto him, Surely, as the Lord liveth, thou hast been upright, and thy going out and thy coming in with me in the host is good in my sight: for I have not found evil in thee since the day of thy coming unto me unto this day: nevertheless the lords favour thee not.

Wherefore now return, and go in peace, that thou displease not the lords of the Philistines.

And David said unto Achish, But what have I done? and what hast thou found in thy servant so long as I have been with thee unto this day, that I may not go fight against the enemies of my lord the king?