Estoppel by silence

if A sells and conveys his slaves or lands, and then produces to another his previous paper title, and obtains credit upon the goods or lands by pledging them for money loaned, he is guilty of a fraud; and if the true owner stands by and does not make his title known, he will be bound to make good the contract; on the principle that he who holds his peace when he ought to have spoken, shall not be heard now that he should be silent. He is deemed in equity a party to the fraud.