1 Samuel 21:13-15

VIN(i) 13 So he changed his behavior before them and pretended to be mad in their presence. He made scratches on the doors of the gate and let his saliva run down into his beard. 14 Then Achish says to his servants, Behold, you see the man is insane: Why bring him to me? 15 have I lack of madmen, that ye have brought this one to rave in my presence? shall this [man] come into my house?