In 1 Samuel 20 we see David is on the run from Saul.  In Chapter 21:10-15 he flees to Achish Gath to seek safety for his life.  Since it had been years since he killed Goliath, who was from Gath, he thought that he could go unrecognized.  But someone there remembered him and said, “And the servants of Achish said unto him, Is not this David the king of the land? did they not sing one to another of him in dances, saying, Saul hath slain his thousands, and David his ten thousands?” (11).  When David heard this he became fearful and acted like a madman, he began to scratch marks on the wall and let spit fall down upon his beard (13).  At this point they left David alone.  It was the belief by some that crazy people were touched by the gods and anyone who hurt them would have to face their wrath.  In the superscription of Psalm 34 we read this is a Psalm of David “when he changed his behavior before Abimelech (the title for a king), who drove him away, and he departed.”