"To hear something straight from the horse's mouth."- it means that you learn some information form the person who it might concern or from the very source

Буквално: чувам нещо направо от устата на коня

Значение: научавам информация от извора; от първа ръка

Example: There won't be any bonuses for this month. I heard it straight from the horse's mouth, I just have been to the boss' office.