1 Samuel 21:13-15

13So he 1disguised his sanity before them, and acted insanely in their hands, and scribbled on the doors of the gate, and let his saliva run down into his beard.

14Then Achish said to his servants, “Behold, you see the man behaving as a madman. Why do you bring him to me?

15Do I lack madmen, that you have brought this one to act the madman in my presence? Shall this one come into my house?”