1 Samuel 21:13 in the World English Bible
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.
Context
12 And David laid up these words in his heart, and was sore afraid of Achish the king of Gath.
13 And he changed his behaviour before them, and feigned himself mad in their hands, and scrabbled on the doors of the gate, and let his spittle fall down upon his beard.
14 Then said Achish unto his servants, Lo, ye see the man is mad: wherefore then have ye brought him to me?