United States Postal Service creed
"Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds" is a phrase long associated with the American postal worker. Though not an official creed or motto of the United States Postal Service, the Postal Service does acknowledge it as an informal motto along with a slightly revised version of Charles W. Eliot's poem "The Letter".
Source: Wikipedia — United States Postal Service creed (CC BY-SA 4.0)