Well, your purchase is within the Statute of Frauds and the law says the contract must be in writing, specifies essential terms such as quantity, subject matter, price, time to performance, and SIGNED by the person to be charged.
However, the law also said that when the vendee tendered payment AND made some modifications of the property which can only be explained by the ownership, the Statute of Frauds does not apply.
You can sue him for breach of contract if he wants to do that.