There were Hebrews who served the Philistines in the past and who stayed in the Philistine camp. But now these Hebrews joined the Israelites with Saul and Jonathan.
But the Philistine captains were angry with Achish. They said, “Send David back! David must go back to the city you gave him. He can’t go with us into battle. {If he is here} we will have an enemy in our own camp. He would make his king happy by killing our men.