David and his followers eventually find relief from King Saul's relentless pursuit by turning to the enemies Saul has been unable to defeat, the Philistines. Israelites had infantry, but Philistines had countless infantry and a chariot corps of 3,000 chariots and 6,000 horses.
Saul decided not to follow David into the coastal plains of Philistine territory, and certainly not into the Philistine town of Gath, where David went.
It seems odd David would go there for safety, to the hometown of the Philistine hero David killed in mortal combat, Goliath. But the city king, Achish, welcomed him as a powerful ally and a fellow enemy of Saul.
That's what the king thought. He was mistaken.
David the raider
David and his men made a living as raiders. They raided enemies of Israel and friends of the Philistines. They raided enemies of Israel: people from Geshur, Gezer, and Amalek who had settled in the southern territory between Telam and Shur, near Egypt.When David and his men attacked a community, they killed all the people. But they kept the livestock and gave it to King Achish: sheep, cattle, donkeys, camels. They gave him stolen clothing as well.King Achish would respond to the gifts by asking, “Who’d you raid today?” David would lie and say he raided Israel or their allies: “We raided the Negev land in Judah.” “We raided the Jerahmeel families in the Negev.” “We raided Kenites in the Negev.”No victims could dispute David. He killed them all. David kept pitching his lies to the king, one raid after another. He did this for as long as he lived among the Philistines.Achish thought he had a solid ally in David—someone who would never move away. The king figured that after all those raids David made on his own people in Israel, they must hate his guts.
The story is in 1 Samuel 27. To compare The Casual English Bible version with other translations, see Bible Gateway.