1 Samuel 29:4-5

But the Philistine commanders were angry with Achish and said, “Send David back to the city you gave him. He cannot go with us into battle. If he does, we’ll have an enemy in our own camp. He could please his king by killing our own men. David is the one the Israelites dance and sing about, saying: ‘Saul has killed thousands of his enemies, but David has killed tens of thousands.’ ”