What are the items regarding which Riba (usury/interest) is prohibited?
Items regarding which Riba is prohibited are gold, silver, wheat, barley, dates and salt. Moreover, Riba is prohibited regarding whatever items that have the same `Illah (effective cause) of Riba for the six varieties which are mentioned above. Such `Illah is value with regard to gold and silver, and measurement along with having a taste concerning the rest of the categories according to the proper opinion of scholars.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.