1 Samuel 21:13-15

Young's Literal Translation

¹³ and changeth his behaviour before their eyes, and feigneth himself mad in their hand, and scribbleth on the doors of the gate, and letteth down his spittle unto his beard.

¹⁴ And Achish saith unto his servants, `Lo, ye see a man acting as a madman; why do ye bring him in unto me?

¹⁵ A lack of madmen [have] I, that ye have brought in this one to act as a madman by me! doth this one come in unto my house?'