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.
Sunan Abi Dawud Book 23, Hadith 23
← Previous Hadith The Prophet (ﷺ) owed me a debt and gave me something extra when he paid it.

Sunan Abi Dawud Book 23, Hadith 22 Next Hadith → 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 being made on the spot. Do not sell them if they are to be paid for later. There is no harm in selling wheat for barley and barley (for wheat) in unequal measure, payment being made on the spot. If the payment is to be made later, then do not sell them.

Abu Dawud said: This tradition has also been transmitted by Sa'id b. Abi 'Arubah, Hisham al-Dastawa'i and Qatadah from Muslim b. Yasar through his chain.

Sunan Abi Dawud Book 23, Hadith 24