David said to Ahimelech the priest, The king has commanded me a business, and has said to me, Let no man know anything of the business about which I send you, and what I have commanded you: and I have appointed the young men to such and such a place.
Now it does definitely declare that David was afraid of Achish. The fear of man can oftentimes cause a person to act like a fool. It brings a snare. So my brave David, he's not afraid of the giant, he's afraid of the king. So acting like a madman, he's reduced to a man with spit running down his beard and scrabbling on the doors and gates, but he did escape out of the hand of Achish. "