All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Al-Mawsoo‘ah Al-Fiqhiyyah Al-Kuwaitiyyah summarized this ruling under the subtitle of selling non-Riba items:
There are two kinds of Riba items:
a- The stated items in the two Hadeeths of ‘Ubaadah and Abu Sa‘eed .
b- Items which meet the cause of forbidding Riba, and their ruling differs according to scholars’ difference on the cause.
Shaafi‘i scholars and the most correct narration maintained by the Hanbali scholars stated that it is permissible to deal in any item or category other than these categories in terms of exchanging an item of one kind for two or more items of the same kind, due to their variable qualities, or deferring the payment or departing before receiving the price. ‘Abdullaah ibn ‘Amr ibn Al-‘Aas said, “The Messenger of Allaah, sallallaahu ‘alayhi wa sallam, commanded me to equip an army, but the camels were insufficient. So, he commanded me to keep back the young camels of charity, and I would take a camel to be replaced by two when the camels of charity came.”
It is reported that ‘Ali sold a camel in return for twenty camels to be received after a time. Ibn ‘Abbaas sold one camel in return for four camels. Ibn ‘Umar bought a female riding-camel for four camels and he guaranteed to give them in full to the buyer at Ar-Rabathah. Raafi‘ ibn Khadeej bought a camel in return for two camels. He gave the seller one camel and told him that he would bring the other camel on the next day.
Hanafi scholars and one of the narrated two opinions from the Hanbali school of Fiqh forbade selling something in return for another of the same kind in deferred payment such as selling one animal to another of the same kind. They based their opinion on the Hadeeth which Samurah traced back to the Prophet, sallallaahu ‘alayhi wa sallam, saying, “The Messenger of Allaah, sallallaahu ‘alayhi wa sallam, forbade selling an animal in return for an animal of the same kind with deferred payment.” Moreover, similarity of kind is one of the causes of prohibition of Riba Al-Fadhl (exchanging an item of one kind for two or more items of the same kind due to their variable qualities). So, deferring payment becomes unlawful in a way similar to measuring and weighing.
According to Maaliki scholars, Riba is fulfilled in any category other than Riba categories such as food, animals and anything to be possessed when three conditions are fulfilled: increase, deferred payment and identicalness of purposes and benefits, such as selling one garment in return for two garments to be paid after a deferred period of time and to sell a riding horse in return for two horses to be paid after a deferred period of time. If only one of the two horses was for riding, the transaction will be permissible because of variation of benefits.
Allaah Knows best.