1 Samuel 28:1-2

While David was living in Ziklag, the Philistines gathered their army together. They planned to fight against Israel. Achish said to David, “Here is what you must understand. You and your men must march out with me and my army.” David said, “I understand. You will see for yourself what I can do.” Achish replied, “All right. I’ll make you my own personal guard for life.”