{slang} Directly from the person or place where it began; from a reliable source or a person that cannot be doubted. * /They are going to be married. I got the news straight from the horse's mouth - their minister./ * /John found out about the painting straight from the horse's mouth, from the painter himself./
STRAIGHT FROM THE HORSE'S MOUTH
Meaning of STRAIGHT FROM THE HORSE'S MOUTH in English
Dictionary of English idioms . Словарь английских идиом. 2012