1 Samuel 29:2 (KJV)

Now the Philistines gathered together all their armies to Aphek: and the Israelites pitched by a fountain which is in Jezreel.

And the lords of the Philistines passed on by hundreds, and by thousands: but David and his men passed on in the rereward with Achish.

Then said the princes of the Philistines, What do these Hebrews here? And Achish said unto the princes of the Philistines, Is not this David, the servant of Saul the king of Israel, which hath been with me these days, or these years, and I have found no fault in him since he fell unto me unto this day?

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?