David replied, “Then you will come to know what your servant can do.”
David answers Achish that he will see what his servant can do, speaking in a way that reveals little about his real intent.
It keeps David's position ambiguous as the conflict closes in.
1Now in those days the Philistines gathered their forces for warfare against Israel. So Achish said to David, “You must understand that you and your men are to go out to battle with me.” 2David replied, “Then you will come to know what your servant can do.” 3Now by this time Samuel had died, and all Israel had mourned for him and buried him in Ramah, his own city. And Saul had removed the mediums and spiritists from the land. 4The Philistines gathered together and camped at Shunem, while Saul gathered all Israel and camped at Gilboa. 5When Saul saw the Philistine army, he was afraid and trembled violently. 6He inquired of the LORD, but the LORD did not answer him by dreams or Urim or prophets.