John Wesley on 1 Samuel 21:10

To Achish - A strange action; but it must be considered, that Saul's rage was so great, his power also, and diligence in hunting after him that he despaired of escaping any other way: and a desperate disease, produceth a desperate remedy. The king elect is here an exile: anointed to the crown, and yet forced to run his country. So do God's providences sometimes run counter to his promises, for the trial of our faith, and the glorifying his name in accomplishing his counsels, notwithstanding the difficulties that lie in the way.