1 Samuel 21:10

7 Now a certain man of the servants of Saul was there that day, detained before the LORD; and his name was Doeg the Edomite, the best of the herdsmen who belonged to Saul.

8 David said to Ahimelech, “Isn’t there here under your hand spear or sword? For I haven’t brought my sword or my weapons with me, because the king’s business required haste.”

9 The priest said, “Behold, the sword of Goliath the Philistine, whom you killed in the valley of Elah, is here wrapped in a cloth behind the ephod. If you would like to take that, take it, for there is no other except that here.” David said, “There is none like that. Give it to me.”

10 David arose and fled that day for fear of Saul, and went to Achish the king of Gath.

11 The servants of Achish said to him, “Isn’t this David the king of the land? Didn’t they sing to one another about him in dances, saying, ‘Saul has slain his thousands, and David his ten thousands’?”

12 David laid up these words in his heart, and was very afraid of Achish the king of Gath.

13 He changed his behavior before them and pretended to be insane in their hands, and scribbled on the doors of the gate, and let his spittle fall down on his beard.