1 Samuel 28:1,2

Preparations for Saul's Last Battle, 1 Samuel 28:1 to 1 Samuel 29:11.

David With Achish in Battle. 1 Samuel 28:1-2

And it came to pass in those days, that the Philistines gathered their armies together for warfare, to fight with Israel. And Achish said unto David, Know thou assuredly, that thou shalt go out with me to battle, thou and thy men.
2 And David said to Achish, Surely thou shalt know what thy servant can do. And Achish said to David, Therefore will I make thee keeper of mine head for ever.

1.

What was the demand of Achish on David? 1 Samuel 28:1

In exchange for the protection which David had received from Achish, David was expected to serve as a soldier with the Philistines. This was a high price to pay for the little bit of security which the Philistines afforded David. It has well been said that he who gives up a bit of his liberty in order to insure some security is worthy neither of liberty or security. David found himself in a position where he was expected to fight with the Philistines against his own people.

2.

Did David intend to fight against Saul? 1 Samuel 28:1-2

While David was living in Philistia, the Philistines gathered their armies together for a campaign against Israel. Achish sent word to David that he was to go with him in his army along with his own men. David answered ambiguously. His words contained no distinct promise of faithful assistance in the war against the Israelites. There are no grounds for inferring that David was disposed to help the Philistines against Saul and the Israelites. Judging from his previous acts, it would necessarily have been against his principles for him to fight against his own people. Nevertheless, in the situation in which he was placed he did not venture to give a distinct refusal to the summons of the king. He was undoubtedly hoping that God would show him a way out of the conflict between his conviction and his duty to obey the Philistine king. He had no doubt prayed earnestly about it; and the faithful God helped his servant; first of all, by the fact that Achish accepted his indefinite declaration as a promise of unconditional fidelity and still more by the fact that the princes of the Philistines overrode the king.