21:10-15 God's persecuted people have often found better usage from Philistines than from Israelites. David had reason to put confidence in Achish, yet he began to be afraid. His conduct was degrading, and discovered wavering in his faith and courage. The more simply we depend on God, and obey him, the more comfortably and surely we shall walk through this troublesome world.

13. feigned himself mad—It is supposed to have been an attack of epilepsy, real or perhaps only pretended. This disease is relieved by foaming at the mouth.

let his spittle fall down upon his beard—No wonder that Achish supposed him insane, as such an indignity, whether done by another, or one's self, to the beard, is considered in the East an intolerable insult.