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. (1 Samuel 28:1)
Thou shalt go out.
This was not an invitation but an order. David, as a vassal of Achish, was under the heathen king’s command. The Philistine ruler had checked David’s movements during the past months, and what he had heard had satisfied him that David had become so closely knit to the Philistines that the Israelite troops would be a valuable addition to the expeditionary force moving north in a few days.
Saul’s Last Battle Against the Philistines 1 Samuel 28-31
