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.  

قَالَ رَسُولُ اللَّهِ ﷺ الذَّهَبُ بِالذَّهَبِ رِبًا إِلاَّ هَاءَ وَهَاءَ وَالْبُرُّ بِالْبُرِّ رِبًا إِلاَّ هَاءَ وَهَاءَ وَالتَّمْرُ بِالتَّمْرِ رِبًا إِلاَّ هَاءَ وَهَاءَ وَالشَّعِيرُ بِالشَّعِيرِ رِبًا إِلاَّ هَاءَ وَهَاءَ  

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.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ الذَّهَبُ بِالذَّهَبِ تِبْرُهَا وَعَيْنُهَا وَالْفِضَّةُ بِالْفِضَّةِ تِبْرُهَا وَعَيْنُهَا وَالْبُرُّ بِالْبُرِّ مُدْىٌ بِمُدْىٍ وَالشَّعِيرُ بِالشَّعِيرِ مُدْىٌ بِمُدْىٍ وَالتَّمْرُ بِالتَّمْرِ مُدْىٌ بِمُدْىٍ وَالْمِلْحُ بِالْمِلْحِ مُدْىٌ بِمُدْىٍ فَمَنْ زَادَ أَوِ ازْدَادَ فَقَدْ أَرْبَى وَلاَ بَأْسَ بِبَيْعِ الذَّهَبِ بِالْفِضَّةِ وَالْفِضَّةُ أَكْثَرُهُمَا يَدًا بِيَدٍ وَأَمَّا نَسِيئَةً فَلاَ وَلاَ بَأْسَ بِبَيْعِ الْبُرِّ بِالشَّعِيرِ وَالشَّعِيرُ أَكْثَرُهُمَا يَدًا بِيَدٍ وَأَمَّا نَسِيئَةً فَلاَ  

"He said: If these classes differ, sell as you wish if payment is made on the spot."  

عَنِ النَّبِيِّ ﷺ بِهَذَا الْخَبَرِ يَزِيدُ وَيَنْقُصُ وَزَادَ قَالَ فَإِذَا اخْتَلَفَتْ هَذِهِ الأَصْنَافُ فَبِيعُوا كَيْفَ شِئْتُمْ إِذَا كَانَ يَدًا بِيَدٍ