1 Samuel 27:10-12

10When Achish asked, “Where did you go raiding today?” David would say, “Against the Negev of Judah” or “Against the Negev of Jerahmeel” or “Against the Negev of the Kenites.”

11He did not leave a man or woman alive to be brought to Gath, for he thought, “They might inform on us and say, ‘This is what David did.’ ” And such was his practice as long as he lived in Philistine territory.

12Achish trusted David and said to himself, “He has become so obnoxious to his people, the Israelites, that he will be my servant for life.”