Is it permissible for me to sell goods online without possessing them at the time of the contract, with my profit derived from the buyer's ignorance of the true price of the commodity, and to retain the deposit if the buyer backs out?

It is not permissible to sell something that the seller does not own or has not taken possession of, with the exception of Bay' al-Salam (forward sale) under specific conditions. It is also permissible to display products without concluding a sales contract. If the buyer requests the merchandise and promises to purchase it, the seller may then acquire it and subsequently sell it to the buyer.

For a sale that was not originally concluded, the merchandise or its value must be returned to the buyer, and its price must be refunded to him. It is not permissible to benefit from the money earned from such a transaction. However, if a new contract is made after the goods have been purchased, then the sale is permissible, and the profit is lawful.

As for the earnest money (Arbun), there are two cases: - If the sales contract is concluded and the sold item is owned by the seller, then the Arbun is permissible according to the Hanbalis. - If the Arbun is paid before the sales contract is concluded and the buyer retracts, then the Arbun must be returned to him.