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  

"O people, you have invented kinds of transactions, I do not know what they are, but make sure it is gold for gold, of the same weight, or silver for silver, of the same weight. There is nothing wrong with selling silver for gold, hand to hand, giving more silver than gold, but no credit is allowed. When you sell wheat for wheat and barley for barley, it should be measure for measure, but there is nothing wrong with selling barley for wheat, hand to hand, giving more barley than wheat, but no credit is allowed. And when you sell dates for dates, it should be measure for measure" And he mentioned salt, "measure for measure, and whoever gives more or asks for more has engaged in Riba. (Using translation from Nasāʾī 4563)  

عَنْ عُبَادَةَ بْنِ الصَّامِتِ وَكَانَ بَدْرِيًّا وَكَانَ بَايَعَ رَسُولَ اللهِ ﷺ أَنْ لَا يَخَافَ فِي اللهِ لَوْمَةَ لَائِمٍ أَنَّ عُبَادَةَ بْنَ الصَّامِتِ قَامَ خَطِيبًا فَقَالَ أَيُّهَا النَّاسُ إِنَّكُمْ قَدْ أَحْدَثْتُمْ بُيُوعًا لَا أَدْرِي مَا هِيَ أَلَا إِنَّ الذَّهَبَ بِالذَّهَبِ وَزْنًا بِوَزْنٍ تِبْرُهَا وَعَيْنُهَا وَإِنَّ الْفِضَّةَ بِالْفِضَّةِ وَزْنًا بِوَزْنٍ تِبْرُهَا وَعَيْنُهَا وَلَا بَأْسَ بِبَيْعِ الْفِضَّةِ بِالذَّهَبِ يَدًا بَيْدٍ وَالْفِضَّةُ أَكْثَرُهُمَا وَلَا تَصْلُحُ نَسِيئَةً أَلَا إِنَّ الْبُرَّ بِالْبُرِّ وَالشَّعِيرَ بِالشَّعِيرِ مُدْيًا بِمُدْيٍ وَلَا بَأْسَ بِبَيْعِ الشَّعِيرِ بِالْحِنْطَةِ يَدًا بَيْدٍ وَالشَّعِيرُ أَكْثَرُهُمَا وَلَا يَصْلُحُ نَسِيئَةً أَلَا وَإِنَّ التَّمْرَ بِالتَّمْرِ مُدْيًا بِمُدْيٍ حَتَّى ذَكَرَ الْمِلْحَ مُدْيًا بِمُدْيٍ فَمَنْ زَادَ أَوِ اسْتَزَادَ فَقَدْ أَرْبَى  

[Machine] O people, you have introduced transactions, I don't know what they are. And indeed, gold with gold should be hand to hand in equal amounts, and silver with silver should be hand to hand in equal amounts. Women should not be exchanged for women, and barley should be exchanged for barley, measure for measure, hand to hand. It is permissible to exchange barley for wheat and the majority of them can be hand to hand. Women should not be exchanged for bad ones. Dates with dates should be exchanged until the salt is counted with salt, like for like, hand to hand. Whoever adds or increases, then he has committed riba. Qatadah said, "Ubadah bin Samit, one of the leaders of the Ansar, gave allegiance to the Messenger of Allah ﷺ that he would not fear the blame of any blamer."  

يَا أَيُّهَا النَّاسُ إِنَّكُمْ قَدْ أَحْدَثْتُمْ بُيُوعًا مَا أَدْرِي مَا هِيَ؟ وَإِنَّ الذَّهَبَ بِالذَّهَبِ تِبْرُهُ وَعَيْنُهُ وَزْنًا بِوَزْنٍ يَدًا بِيَدٍ وَالْفِضَّةُ بِالْفِضَّةِ وَزْنًا بِوَزْنٍ يَدًا بِيَدٍ وَلَا يَصْلُحُ نَسَاءً وَالْبُرُّ بِالْبُرِّ مُدًّا بِمُدٍّ يَدًا بِيَدٍ وَالشَّعِيرُ بِالشَّعِيرِ مُدًّا بِمُدٍّ يَدًا بِيَدٍ وَلَا بَأْسَ بِبَيْعِ الشَّعِيرِ بِالْبُرِّ وَالشَّعِيرُ أَكْثَرُهُمَا يَدًا بِيَدٍ وَلَا يَصْلُحُ نَسِيئَةً وَالتَّمْرُ بِالتَّمْرِ حَتَّى عَدَّ الْمِلْحَ بِالْمِلْحِ مِثْلًا بِمِثْلٍ يَدًا بِيَدٍ مَنْ زَادَ أَوِ ازْدَادَ فَقَدْ أَرْبَى قَالَ قَتَادَةُ وَكَانَ عُبَادَةُ بَدْرِيًّا عَقَبِيًّا أَحَدَ نُقَبَاءِ الْأَنْصَارِ وَكَانَ بَايَعَ رَسُولَ اللهِ ﷺ عَلَى أَنْ لَا يَخَافَ فِي اللهِ لَوْمَةَ لَائِمٍ كَذَا  

"الذَّهَبُ بالذَّهَبِ تِبْرُهَا وَعَيها، والفِضَّةُ بالفِضَّة تِبْرهَا وَعَينُهَا، وَالبُرُّ بالبُرُّ مُدَّين بمُدَّين، والشَّعيرُ بالشَّعِير مُدَّين بمُدَّين، والتَّمْرُ بالتَّمْرُ مُدَّين بِمُدَّين والمِلحُ بالملِح مُدَّين بمدَّين، فَمَنْ زَادَ أوْ ازْدَادَ فَقَدْ أرْبى، وَلَا بَأس بِبَيعِ الذَّهَب بِالفِضَّةِ والفِضَّة بالذَّهَبِ أَكثَرَهما يَدًا بيَدٍ، وأما نَسيئَه فلا، ولا بَأسَ ببَيع البُرُّ بالشَّعِير، والشَّعِير بالبُرِّ أَكثَرَهما يَدًا بيدٍ وأما نسيئةً فَلَا".