Charles Ellicott Commentary 1 Samuel 21:10

"And David arose, and fled that day for fear of Saul, and went to Achish the king of Gath." — 1 Samuel 21:10 (ASV)

And David arose and fled —The cause of this sudden flight was, of course, the fear of Doeg, one of Saul’s most trusted servants. Not an hour must be lost, thought David; my deadly foe will hear that I am here, and I shall be trapped like a hunted beast of prey. It seems at first sight strange that David should dare to go among the Philistines, who had such good cause to hate and fear him, but the son of Jesse always thought little of himself, and had no idea that his person was so well known, or his story so widely known as it subsequently proved to be. (See 1 Samuel 21:11).

Of David’s humility, so conspicuously exhibited on this occasion, when he ventured among his foes, not dreaming how great a personage they considered him, the Babylonian Talmud strikingly writes:—“No man in Israel despised himself more than David regarding the Lord’s precepts, and this is what he said before God (Psalms 131:1–2), ‘Lord, my heart was not haughty when Samuel anointed me king, nor were my eyes lofty when I slew Goliath ... as a child ... I have made myself like a child before You, in not being ashamed to humble myself before You for Your glory.’”—Treatise Bamidbar, chapter 4.

Achish the king of Gath. —The title “king” is somewhat loosely used in this scene among the Philistines. Achish was one of the Philistine lords, perhaps the hereditary lord of Gath. Achish is called Abimelech in the title of Psalms 34:0, that apparently being the title, the “nomen dignitatis,” of the hereditary (or elected) chief among the Philistines, like Agag among the Amalekites. It is quite possible that this Achish, although called king of Gath, was the supreme chief or king of the Philistine nation. Gath was the nearest Philistine city to the sanctuary of Nob where David then was.