Albert Barnes 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)

Achish king of Gath - It appears from the title of Psalm 34 that it was composed on this occasion. (See the note there.) Nothing can give a more vivid impression of the difficult circumstances David faced than the fact that he went to the country of the Philistines.