"I used to sell camels, and I used to buy gold for silver and silver for gold, Dinar for Dirham and Dirham for Dinar. I asked the Prophet ﷺ about that, and he said: 'If you take one of them and give the other, then you and your companion should not separate until everything is clear (i.e., the exchange is completed).’” (Hasan) Another chain with similar wording.
كُنْتُ أَبِيعُ الإِبِلَ فَكُنْتُ آخُذُ الذَّهَبَ مِنَ الْفِضَّةِ وَالْفِضَّةَ مِنَ الذَّهَبِ وَالدَّنَانِيرَ مِنَ الدَّرَاهِمِ وَالدَّرَاهِمَ مِنَ الدَّنَانِيرِ فَسَأَلْتُ النَّبِيَّ ﷺ فَقَالَ إِذَا أَخَذْتَ أَحَدَهُمَا وَأَعْطَيْتَ الآخَرَ فَلاَ تُفَارِقْ صَاحِبَكَ وَبَيْنَكَ وَبَيْنَهُ لَبْسٌ حَدَّثَنَا يَحْيَى بْنُ حَكِيمٍ حَدَّثَنَا يَعْقُوبُ بْنُ إِسْحَاقَ أَنْبَأَنَا حَمَّادُ بْنُ سَلَمَةَ عَنْ سِمَاكِ بْنِ حَرْبٍ عَنْ سَعِيدِ بْنِ جُبَيْرٍ عَنِ ابْنِ عُمَرَ عَنِ النَّبِيِّ ﷺ نَحْوَهُ