1 Samuel 28:1
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. 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.
The verse belongs to a renewed war between Israel and the Philistines, with the Philistine forces gathered at Shunem and Saul's forces encamped near Mount Gilboa. Saul's relentless pursuit of David had left the defenses of the kingdom neglected, which allowed the Philistines to penetrate far into Israel. The Philistines were assembling for warfare against Israel, and Achish required David and his men to go out with him to battle.
The Philistines welcomed the chance to separate David's forces from Saul's army, hoping David would seize the opportunity to avenge his wrongs by fighting against Saul and Israel. David had no intention of fighting against his own people, but he was uncertain what to do until circumstances made his duty clear, so he answered evasively. Achish took his words as a promise of aid and offered him honor and high office, even a high position as reward.
Saul feared that David would use the opportunity to avenge the wrongs he had suffered at Saul's hands. When Saul faced the Philistine army he trembled, because he felt alone and defenseless after God had forsaken him. The setting stands in contrast to Gideon's victory, which was won through faith in God.