"The Messenger of Allah said: 'Dates for dates, wheat for wheat, barley for barley, salt for salt, exchanged hand to hand. Whoever gives more or takes more has engaged in Riba unless they are of different types." (Using translation from Nasāʾī 4559)
قَالَ رَسُولُ اللهِ ﷺ الْحِنْطَةُ بِالْحِنْطَةِ وَالشَّعِيرُ بِالشَّعِيرِ وَالتَّمْرُ بِالتَّمْرِ وَالْمِلْحُ بِالْمِلْحِ كَيْلًا بِكَيْلٍوَوَزْنًا بِوَزْنٍ فَمَنْ زَادَ أَوِ ازْدَادَ فَقَدْ أَرْبَى إِلَّا مَا اخْتَلَفَ أَلْوَانُهُ