1 Samuel 28:1-2

American Standard Version

28 And it came to pass in those days, that the Philistines gathered their ^[a]hosts together for warfare, to fight with Israel. And Achish said unto David, Know thou assuredly, that thou shalt go out with me in the host, thou and thy men. ² And David said to Achish, Therefore thou shalt know what thy servant will do. And Achish said to David, Therefore will I make thee keeper of my head for ever.