1 Samuel 27:8-12

Now David and his men went up and attacked the Geshurites, the Girzites, and the Amalekites; for they were the inhabitants of the land from ancient times, as you come to Shur even as far as the land of Egypt.

David attacked the land and did not leave a man or a woman alive, and he took the sheep, the cattle, the donkeys, the camels, and the clothing. Then he returned and came to Achish.

Now Achish said, “Where did you carry out an attack today?” And David said, “Against the Negev of Judah, against the Negev of the Jerahmeelites, and against the Negev of the Kenites.”

And 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.’ ”

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