When a contract is made on another person's property, when is the sale valid?

The questioner : When the contract is made on the property of another... if the owner approves it, it is permissible, is the sale valid, O Shaykh, in principle? It is valid... on the property of another, and even if he approves it, because it was not valid for him.

The Shaykh : Yes, it is valid; it was not valid for him. It is pending approval. Even if he sells the property of another without permission and then the owner approves it, the sale is valid.