1 Samuel 27:9-11

9Whenever David's men attacked them, they killed all the men and women. But they took all their sheep, cows, donkeys and camels, as well as their clothes. Then they would return to see King Achish.

10Achish would ask David, ‘Which place did you go and attack today?’ Sometimes David would say, ‘We robbed the people of a town in Judah's desert.’ Or David might say, ‘We attacked a town in the desert where the people of Jerahmeel's clan live.’ Or he might say, ‘We attacked a town in the desert where the Kenites live.’

11David killed all the people in the places that he attacked. He never took anyone back to Gath. He thought, ‘If any of the people are still alive, they might go to Gath and tell people what we have done.’ That is what David did for the whole time that he lived among the Philistines.