1 Samuel 21:13-15

13so he pretended to be insane in their presence. He acted like a madman around them, scribbling on the doors of the city gate and letting saliva run down his beard.

14“Look! You can see the man is crazy,” Achish said to his servants. “Why did you bring him to me?

15Do I have such a shortage of crazy people that you brought this one to act crazy around me? Is this one going to come into my house?”