1 Samuel 27:10-12

10Now Achish said, “1Where did you 2carry out an attack today?” And David said, “Against the 3Negev of Judah, against the 4Negev of 5the Jerahmeelites, and against the 6Negev of 7the Kenites.”

11And David did not leave a man or a woman alive to bring to Gath, saying, “Otherwise they will tell about us, saying, ‘This is what David has done, and this has been his practice all the time that he has lived in the country of the Philistines.’”

12So Achish believed David, saying, “He has undoubtedly made himself repulsive among his people Israel; therefore he will become my servant forever.”