Abu Sa'id al-Khudri (Allah be pleased with him) reported Allah's Messenger (ﷺ) as saying:Gold is to be paid for by gold, silver by silver, wheat by wheat, barley by barley, dates by dates, salt by salt, like by like, payment being made hand to hand. He who made an addition to it, or asked for an addition, in fact dealt in usury. The receiver and the giver are equally guilty.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ مُسْلِمٍ الْعَبْدِيُّ، حَدَّثَنَا أَبُو الْمُتَوَكِّلِ النَّاجِيُّ، عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " الذَّهَبُ بِالذَّهَبِ وَالْفِضَّةُ بِالْفِضَّةِ وَالْبُرُّ بِالْبُرِّ وَالشَّعِيرُ بِالشَّعِيرِ وَالتَّمْرُ بِالتَّمْرِ وَالْمِلْحُ بِالْمِلْحِ مِثْلاً بِمِثْلٍ يَدًا بِيَدٍ فَمَنْ زَادَ أَوِ اسْتَزَادَ فَقَدْ أَرْبَى الآخِذُ وَالْمُعْطِي فِيهِ سَوَاءٌ " .
Muslim
The Book of Musaqah • Hadith 103