I used to practice money exchange, and I asked Zaid bin 'Arqam about it, and he narrated what the Prophet said in the following: Abu Al-Minhal said, "I asked Al-Bara' bin ʿAzib and Zaid bin Arqam about practicing money exchange. They replied, 'We were traders in the time of Messenger of Allah ﷺ and I asked Messenger of Allah ﷺ about money exchange. He replied, 'If it is from hand to hand, there is no harm in it; otherwise it is not permissible."  

قَالَ النَّبِيُّ ﷺ وَحَدَّثَنِي الْفَضْلُ بْنُ يَعْقُوبَ حَدَّثَنَا الْحَجَّاجُ بْنُ مُحَمَّدٍ قَالَ ابْنُ جُرَيْجٍ أَخْبَرَنِي عَمْرُو بْنُ دِينَارٍ وَعَامِرُ بْنُ مُصْعَبٍ أَنَّهُمَا سَمِعَا أَبَا الْمِنْهَالِ يَقُولُ سَأَلْتُ الْبَرَاءَ بْنَ عَازِبٍ وَزَيْدَ بْنَ أَرْقَمَ عَنِ الصَّرْفِ فَقَالاَ كُنَّا تَاجِرَيْنِ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ فَسَأَلْنَا رَسُولَ اللَّهِ ﷺ عَنِ الصَّرْفِ فَقَالَ إِنْ كَانَ يَدًا بِيَدٍ فَلاَ بَأْسَ وَإِنْ كَانَ نَسَاءً فَلاَ يَصْلُحُ  

" I asked Al-Bara bin 'Azib and Zaid bin Arqam and they said: 'We were merchants at the time of the Messenger of Allah and we asked the Prophet of Allah about money exchange. He said: "If it is done hand to hand there is nothing wrong with it, but if it is done on credit then it is not right."  

أَخْبَرَنِي عَمْرُو بْنُ دِينَارٍ وَعَامِرُ بْنُ مُصْعَبٍ أَنَّهُمَا سَمِعَا أَبَا الْمِنْهَالِ يَقُولُ سَأَلْتُ الْبَرَاءَ بْنَ عَازِبٍ وَزَيْدَ بْنَ أَرْقَمَ فَقَالاَ كُنَّا تَاجِرَيْنِ عَلَى عَهْدِ رَسُولِ اللَّهِ ﷺ فَسَأَلْنَا نَبِيَّ اللَّهِ ﷺ عَنِ الصَّرْفِ فَقَالَ إِنْ كَانَ يَدًا بِيَدٍ فَلاَ بَأْسَ وَإِنْ كَانَ نَسِيئَةً فَلاَ يَصْلُحُ  

" I asked Al-Bara bin 'Azib and Zaid bin Arqam and they said: 'We were merchants at the time of the Messenger of Allah and we asked the Prophet of Allah about money exchange. He said: "If it is done hand to hand there is nothing wrong with it, but if it is done on credit then it is not right." (Using translation from Nasāʾī 4576)  

أَخْبَرَنِي عَمْرُو بْنُ دِينَارٍ وَعَامِرُ بْنُ مُصْعَبٍ أَنَّهُمَا سَمِعَا أَبَا الْمِنْهَالِ يَقُولُ سَأَلْتُ الْبَرَاءَ بْنَ عَازِبٍ وَزَيْدَ بْنَ أَرْقَمَ فَقَالَا كُنَّا تَاجِرَيْنِ عَلَى عَهْدِ رَسُولِ اللهِ ﷺ فَسَأَلْنَا رَسُولَ اللهِ ﷺ عَنِ الصَّرْفِ فَقَالَ «إِنْ كَانَ يَدًا بَيْدٍ فَلَا بَأْسَ وَإِنْ كَانَ نَسِيئَةً فَلَا يَصْلُحُ»