1 Samuel 27:12

And Achish believed David, saying, He hath made his people Israel utterly to abhor him, making himself a stench, a loathing, completely alienating himself from the Israelites; therefore he shall be my servant forever. Thus Achish was deceived, while David continued to harass and destroy the desert tribes which were a menace to Israel. Thus he, while receiving evil at the hand of Saul, rewarded good to the entire people of Israel, a fine example of love toward one's enemies.