Usurious Gain (Riba) ;
It is unlawful (haram) to do, consume, take, write down, or be a witness to usurious gain (riba). The riba comprises the following ;
1. Selling gold for silver and silver for gold, gold for gold; or silver for silver--whether coined or not, made into jewelry, the ore itself, or other than that--with the condition of postponing the payment; .
2. Selling the aforementioned items with the buyer or seller leaving one another before exchanging the payments;
3. Selling gold for gold or silver for silver with inequality in weight;
4. In the case of selling food for other food: It is not lawful to sell one type of food for another, such as wheat for barley, if one includes the condition of postponing the payment or if the buyer or seller leave one another before exchanging payments. In the case of similar types of food, such as wheat for wheat, one must avoid the aforementioned two conditions along with inequality. Hence, it is not lawful to sell barley for barley if there is inequality in volume, or the condition of postponing the payment is included, or the buyer and seller leave one another before exchanging payment.