Is it permissible to exchange fresh produce of the same type, such as fresh dates for fresh dates or grapes for grapes?
Chapter on Riba (Usury) and Exchange (Sarf)
Al-Mughni
Book of Sales
Primary text
Exchanging fresh produce (rutab) of the same type, like fresh dates for fresh dates, is permissible according to the majority of scholars, provided there is equality (tamathul). This ruling is supported by inferring from the prohibition of exchanging dates for dates, which implies permissibility when they are equal in their current state and neither one is singularly prone to deficiency. This exchange is likened to selling milk for milk or dates for dates when equal. Furthermore, the general permissibility of trade mentioned in the Quran (2:275) remains in force for cases not explicitly prohibited.
Supporting text
Al-Shafi'i prohibited this exchange when the produce is expected to dry out. Furthermore, for items that do not dry out, such as cucumbers or gourds, there are two views because equality at the time of storage cannot be confirmed, making it similar to fresh dates being exchanged for dried dates.