I Samuel 21:2, 13

So David said to Ahimelech the priest, “The king has ordered me on some business, and said to me, ‘Do not let anyone know anything about the business on which I send you, or what I have commanded you.’ And I have directed my young men to such and such a place.

So he changed his behavior before them, pretended madness in their hands, scratched on the doors of the gate, and let his saliva fall down on his beard.