4 Angry with Achish, the Philistine officers said, "Send this man back to where he came from. Let him stick to his normal duties. He's not going into battle with us. He'd switch sides in the middle of the fight! What better chance to get back in favor with his master than by stabbing us in the back!
Matthew Henry's Commentary on 1 Samuel 29:4
Commentary on 1 Samuel 29:1-5
(Read 1 Samuel 29:1-5)
David waited with a secret hope that the Lord would help him out of his difficulty. But he seems to have been influenced too much by the fear of man, in consenting to attend Achish. It is hard to come near to the brink of sin, and not to fall in. God inclined the princes of the Philistines to oppose David's being employed in the battle. Thus their dislike befriended him, when no friend could do him such a kindness.