1 Samuel 29:3-5

3But the Philistine commanders demanded, “What are these Hebrews doing here?” And Achish told them, “This is David, the servant of King Saul of Israel. He’s been with me for years, and I’ve never found a single fault in him from the day he arrived until today.”

4But the Philistine commanders were angry. “Send him back to the town you’ve given him!” they demanded. “He can’t go into the battle with us. What if he turns against us in battle and becomes our adversary? Is there any better way for him to reconcile himself with his master than by handing our heads over to him?

5Isn’t this the same David about whom the women of Israel sing in their dances, ‘Saul has killed his thousands, and David his ten thousands’?”