1 Samuel 27:9-11

9Whenever David attacked a territory, he did not leave a man or woman alive, but he took the flocks and herds, the donkeys, camels, and clothing.

Then he would return to Achish, 10who would ask him, “What have you raided today?”

And David would reply, “The Negev of Judah,” or “The Negev of Jerahmeel,” or “The Negev of the Kenites.”

11David did not leave a man or woman alive to be brought to Gath, for he said, “Otherwise they will report us, saying, ‘This is what David did.’” And this was David’s custom the whole time he lived in Philistine territory.