to hear something straight from the horse's mouth

The phrase "to hear something straight from the horse's mouth" means to receive information directly from the most reliable or authoritative source, typically someone who has direct knowledge or involvement in the matter being discussed. It implies that the information is firsthand and trustworthy. The origin of this phrase can be traced to the practice of examining a horse's teeth to determine its age and health, as information about the horse's condition is most accurate when obtained directly from the animal itself.