And David arose, and {h} fled that day for fear of Saul, and went to Achish the king of Gath.

(h) That is, out of Saul's domain.

Wesley's Notes

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.

Jamieson-Fausset-Brown Bible Commentary

1Sa 21:10-15. At Gath He Feigns Himself Mad.

10. David . fled . to Achish the king of Gath-which was one of the five principalities of the Philistines. In this place his person must have been known, and to venture into that country, he their greatest enemy, and with the sword of Goliath in his hand, would seem to have been a perilous experiment; but, doubtless, the protection he received implies that he had been directed by the divine oracle. Achish was generous (1Sa 27:6). He might wish to weaken the resources of Saul, and it was common in ancient times for great men to be harbored by neighboring princes.

Matthew Henry's Concise Commentary

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.