1 Samuel 27:11-12

And David would leave neither man nor woman alive to bring news to Gath, thinking, “lest they should tell about us and say, ‘So David has done.’” Such was his custom all the while he lived in the country of the Philistines. And Achish trusted David, thinking, “He has made himself an utter stench to his people Israel; therefore he shall always be my servant.”