1 Samuel 28:2 - Clarke's commentary and critical notes on the Bible

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. Surely thou shalt know what thy servant can do - This was another equivocal answer; and could only be understood by his succeeding conduct. It might imply what he could do in favor of the Philistines against Israel; or in favor of Israel against the Philistines. Achish understood it in the former sense; and therefore he said to David, I will make thee keeper of my head for ever; i.e., Thou shalt be captain of my life-guards.