Muhammad bin Uqbah (may Allah have mercy on him) said: Mu'awiyah (may Allah be pleased with him) gave a sermon and said something that the people disapproved of, so they objected to him. Upon that he explained it and said: I heard the Messenger of Allah (peace and blessings be upon him) say: "There will be rulers who will speak and their word will not be rejected; they will tumble into the Fire, one following another."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16839