How sound is the transaction that involves purchasing goods and selling them to customers in installments with a down payment? Is it permissible to buy these goods back after selling them to customers for the purpose of liquidity, and must they be bought back at the same price? Is it permissible to receive checks or an advance payment before delivering the goods as a precaution? Is it permissible to partner with the customer in purchasing the goods such such that the customer owns only 20% of their price? And how is the amount of zakat calculated when payments are received at distant intervals?

The first transaction (Murabaha to a party requesting a purchase) is permissible if it adheres to Sharia guidelines. The second transaction (Bay' al-Inah) is impermissible unless the seller repurchases the item at the same price he sold it for. The third transaction (receiving a check with an upfront installment) is permissible if the commodity is owned by the seller or is a specified obligation (dhimma), and the check has sufficient funds and is certified. It is not permissible to receive part of the price in a salam transaction or to make a non-funded check the capital for a salam transaction. The fourth transaction (customer's participation with a common share) is permissible. Zakat is calculated by evaluating trade goods, adding cash and expected debts, and paying one-quarter of one-tenth (2.5%).