Sahih Bukhari Volume 3, Book 34, Hadith Number 298.

Narated By Samura bin Jundab : The Prophet said, “This night I dreamt that two men came and took me to a Holy land whence we proceeded on till we reached a river of blood, where a man was standing, and on its bank was standing another man with stones in his hands. The man in the middle of the river tried to come out, but the other threw a stone in his mouth and forced him to go back to his original place. So, whenever he tried to come out, the other man would throw a stone in his mouth and force him to go back to his former place. I asked, ‘Who is this?’ I was told, ‘The person in the river was a Riba-eater.”