Sahih al-Bukhari 2174
Narrated Ibn Shihab:
that Malik bin Aus said, "I was in need of change for one-hundred Dinars. Talha bin 'Ubaidullah 
called me and we discussed the matter, and he agreed to change (my Dinars). He took the gold pieces 
in his hands and fidgeted with them, and then said, "Wait till my storekeeper comes from the forest." 
`Umar was listening to that and said, "By Allah! You should not separate from Talha till you get the 
money from him, for Allah's Messenger (ﷺ) said, 'The selling of gold for gold is Riba (usury) except if the 
exchange is from hand to hand and equal in amount, and similarly, the selling of wheat for wheat is 
Riba (usury) unless it is from hand to hand and equal in amount, and the selling of barley for barley is 
usury unless it is from hand to hand and equal in amount, and dates for dates, is usury unless it is from 
hand to hand and equal in amount"
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ مَالِكِ بْنِ أَوْسٍ، أَخْبَرَهُ أَنَّهُ الْتَمَسَ، صَرْفًا بِمِائَةِ دِينَارٍ، فَدَعَانِي طَلْحَةُ بْنُ عُبَيْدِ اللَّهِ فَتَرَاوَضْنَا، حَتَّى اصْطَرَفَ مِنِّي، فَأَخَذَ الذَّهَبَ يُقَلِّبُهَا فِي يَدِهِ، ثُمَّ قَالَ حَتَّى يَأْتِيَ خَازِنِي مِنَ الْغَابَةِ، وَعُمَرُ يَسْمَعُ ذَلِكَ، فَقَالَ وَاللَّهِ لاَ تُفَارِقُهُ حَتَّى تَأْخُذَ مِنْهُ، قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏ الذَّهَبُ بِالذَّهَبِ رِبًا إِلاَّ هَاءَ وَهَاءَ، وَالْبُرُّ بِالْبُرِّ رِبًا إِلاَّ هَاءَ وَهَاءَ، وَالشَّعِيرُ بِالشَّعِيرِ رِبًا إِلاَّ هَاءَ وَهَاءَ، وَالتَّمْرُ بِالتَّمْرِ رِبًا إِلاَّ هَاءَ وَهَاءَ ‏"‏‏.‏