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: Messenger of Allah ﷺ forbade the sale of silver for gold when payment is to be made in future.

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 ﷺ عَنْ بَيْعِ الْوَرِقِ بِالذَّهَبِ دَيْنًا.