Sahih Muslim Book: 23, Hadith: 4156

حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ الْعَنْبَرِيُّ، حَدَّثَنَا أَبِي، حَدَّثَنَا شُعْبَةُ، عَنْ حَبِيبٍ، أَنَّهُ سَمِعَ أَبَا الْمِنْهَالِ، يَقُولُ سَأَلْتُ الْبَرَاءَ بْنَ عَازِبٍ عَنِ الصَّرْفِ، فَقَالَ سَلْ زَيْدَ بْنَ أَرْقَمَ فَهُوَ أَعْلَمُ ‏.‏ فَسَأَلْتُ زَيْدًا فَقَالَ سَلِ الْبَرَاءَ فَإِنَّهُ أَعْلَمُ ثُمَّ قَالاَ نَهَى رَسُولُ اللَّهِ صلى الله عليه وسلم عَنْ بَيْعِ الْوَرِقِ بِالذَّهَبِ دَيْنًا. Habib reported that he heard Abu Minhal as saying:I asked al-Bara’ b. Azib about the exchange of (gold for silver or vice versa), whereupon he said: you better ask Zaid b. Arqam for he knows more than I. So I asked Zaid but he said: You better ask al-Bara’ for he knows more than I. Then both of them said: Allah’s Messenger (may peace be upon him) forbade the sale of silver for gold when payment is to be made in future. Chain : ‘Ubaidullah bin Mua’dh – Mua’dh bin Mua’dh bin Nsr – Shu’bah bin al-Hajjaj – Habib al-Ma’lm Abu Muhammad – Siyar bin Salaama, Abu al-Minhal – al-Bara’ bin