Gold for gold, silver for silver, wheat for wheat, barley for barley, dates for dates, and salt for salt, like for like, equal for equal, hand to hand. If these classes differ, sell as you wish if it is hand to hand

The Prophet (may Allah's peace and blessings be upon him) clarified the correct method of sale involving any of the six Riba-based classes, which are: gold, silver, wheat, barley, dates, and salt. If they are of the same type, such as selling gold for gold and silver for silver, two conditions must be fulfilled: First: Equality in weight if it is weighed, such as gold and silver, or equality in measure if it is measured, such as wheat, barley, dates, and salt.

Second: The seller must receive the payment, and the buyer must take possession of the item in the same session in which the sale contract is made. If these classes differ, such as selling gold for silver or dates for wheat, then the sale is permissible with one condition: the seller must receive the payment, and the buyer must take possession of the item in the same session in which the contract is made.

Otherwise, the sale is invalid, and both the buyer and the seller have fallen into forbidden Riba (usury).