1 Samuel 27:8-9
8-9From time to time David and his men raided the Geshurites, the Girzites, and the Amalekites—these people were longtime inhabitants of the land stretching toward Shur and on to Egypt. When David raided an area he left no one alive, neither man nor woman, but took everything else: sheep, cattle, donkeys, camels, clothing—the works. Then he'd return to Achish.
10-11Achish would ask, "And whom did you raid today?"
David would tell him, "Oh, the Negev of Judah," or "The Negev of Jerahmeel," or "The Negev of the Kenites." He never left a single person alive lest one show up in Gath and report what David had really been doing. This is the way David operated all the time he lived in Philistine country.