1 Samuel 21:9-15 - David Goes To Gath
9 The priest said, "The sword of Goliath the Philistine, whom you struck down in the Valley of Elah is wrapped up in a cloth behind the ephod. If you want it, take it because there is no other except it here." So David said, "There is none like it. Give it to me."
10 David got up that day and fled from Saul, and he went to King Achish of Gath. 11 The officials of Achish told him, "Isn't this David, king of the land? Isn't this the one about whom they sang as they danced, "Saul has struck down his thousands, but David his ten thousands'?"
12 David took these words seriously, and he was very frightened of King Achish of Gath. 13 So David changed his behavior before them and acted like he was crazy in their presence. He scribbled on the doors of the gate, and let his saliva run down his beard.
14 Achish told his officials, "Look, you see a person acting like a madman. Why'd you bring him to me? 15 Am I lacking madmen that you bring me this one to act like a madman around me? Shall this one come into my house?"