Does the ruling on usury related to Bilal’s hadith about selling dates apply to contemporary commercial transactions involving paper currencies, taking into account the utility of goods compared to money, and are these currencies permissible or impermissible?

The hadith narrated by Abu Sa'id Al-Khudri states that Bilal brought the Prophet (peace be upon him) some Barni dates (a type of date). The Prophet (peace be upon him) asked him about its source. Bilal informed him that he had sold two sa's of inferior dates for one sa' to feed the Prophet (peace be upon him). The Prophet (peace be upon him) then said: "Awah, awah! This is the essence of usury! This is the essence of usury! Do not do it! But if you wish to buy, then sell the dates for another sale, then buy it."

The word "Awah" (أَوَّهْ) signifies distress and sorrow, and "essence of usury" (عين الربا) means that it is truly forbidden usury. This is a clear text prohibiting Riba Al-Fadl (usury of surplus) in dates.

As for banknotes, they function as a substitute for gold and silver in transactions, and usury applies to them just as it applies to gold and silver.

The items subject to usury are different categories specified by the Prophet (peace be upon him): gold, silver, wheat, barley, dates, and salt. Riba Al-Fadl is prohibited in these if they are of the same category with an excess; equality in exchange is obligatory.

If these usurious categories differ, then selling is permissible "as you wish if it is hand-to-hand." This means that if the categories differ, equality is not a condition, but immediate possession (hand-to-hand exchange) is required.

Scholars agree on the permissibility of selling a usurious item for another usurious item not of the same category, with a delay and a surplus, such as selling gold for wheat.

The six categories (gold, silver, wheat, barley, dates, salt) are subject to Riba Al-Fadl and Riba Al-Nasi'ah (usury of delay) if one of the same categories is sold for itself. Equality and possession before parting are obligatory. If a usurious item is sold for another item that shares the same reason for usury (measure or weight), then possession before parting is obligatory. However, if it does not share the same reason for usury, then usury does not apply between them, and neither possession nor equality is a condition.

It is permissible to sell a usurious item for a non-usurious item with a surplus and parting before possession.