Ubada bin As-Samit · Commercial Transactions (Kitab Al-Buyu)

The Messenger of Allah (ﷺ) as saying: Gold for gold is interest unless both hand over on the spot ; wheat for wheat is interest unless both hand over on the spot ; dates for dates is interest unless both hand over on the spot ; barley for barley is interest unless both hand over on the spot.

The Messenger of Allah (ﷺ) said: Gold is to be paid for with gold, raw and coined, silver with silver, raw and coined (in equal weight), wheat with wheat in equal measure, barley with barley in equal measure, dates with dates in equal measure, salt by salt with equal measure; if anyone gives more or asks more, he has dealt in usury. But there is no harm in selling gold for silver and silver (for gold), in unequal weight, payment…

Ibn Rawahah assessed them (the amount of dates) at forty thousand wasqs, and when Ibn Rawahah gave them option, the Jews took the fruits in their possession and twenty thousand wasqs of dates were due from them.