straight from the horse's mouth 绝对可靠;直接从马的嘴;从可靠渠道;根据最可靠的消息来源

【例句】
Say, did you hear that Sally and Bob are going to get married? I heard it from Bob himself, so it's straight from the horse's mouth!
喂，听说了没？萨利和鲍勃要结婚了。鲍勃亲自告诉我的，消息绝对可靠！

Lisa will be promoted to manager. The boss told me himself. It's straight from the horse's mouth!
丽萨会升为经理。这是老板亲口告诉我的，绝对真实可靠！