Is it permissible to delay specifying the price of the commodity in a Murabaha to the one who orders the purchase, until one or two days after the buyer receives it, for the purpose of estimating the cost and determining the price and installments? And is it permissible to change the price of the commodity and the number of installments before the final agreement, to accommodate the buyer's ability to pay, taking into consideration the difference between changing that before or after receiving the commodity?

The price must be known when conducting a sale transaction, otherwise, it is invalid. It is not permissible to conclude a sale contract based on an unknown price. Al-Dusuqi said: "The price and the sold item must be known to both the seller and the buyer, otherwise the sale is void." Ibn Abidin said: "A condition for validity is the knowledge of the sold item and its price."

However, after the contract is completed and the price and its installments have been agreed upon, there is no harm in adjusting the installment dates and changing the amount of payments by mutual consent between the seller and the buyer. But it is not permissible to increase the price because of this. There is no difference whether the buyer has taken possession of the goods or not; the decisive factor is the completion of the sale contract.