I used to sell camels at al-Baqi for dinars and take dirhams for them, and sell for dirhams and take dinars for them. I would take these for these and give these for these. I went to the Messenger of Allah ﷺ who was in the house of Hafsah. I said: Messenger of Allah , take it easy, I shall ask you (a question): I sell camels at al-Baqi'. I sell (them) for dinars and take dirhams and I sell for dirhams and take dinars. I take these for these, and give these for these. The Messenger of Allah ﷺ then said: There is no harm in taking them at the current rate so long as you do not separate leaving something to be settled.  

كُنْتُ أَبِيعُ الإِبِلَ بِالْبَقِيعِ فَأَبِيعُ بِالدَّنَانِيرِ وَآخُذُ الدَّرَاهِمَ وَأَبِيعُ بِالدَّرَاهِمِ وَآخُذُ الدَّنَانِيرَ آخُذُ هَذِهِ مِنْ هَذِهِ وَأُعْطِي هَذِهِ مِنْ هَذِهِ فَأَتَيْتُ رَسُولَ اللَّهِ ﷺ وَهُوَ فِي بَيْتِ حَفْصَةَ فَقُلْتُ يَا رَسُولَ اللَّهِ رُوَيْدَكَ أَسْأَلُكَ إِنِّي أَبِيعُ الإِبِلَ بِالْبَقِيعِ فَأَبِيعُ بِالدَّنَانِيرِ وَآخُذُ الدَّرَاهِمَ وَأَبِيعُ بِالدَّرَاهِمِ وَآخُذُ الدَّنَانِيرَ آخُذُ هَذِهِ مِنْ هَذِهِ وَأُعْطِي هَذِهِ مِنْ هَذِهِ فَقَالَ رَسُولُ اللَّهِ ﷺ لاَ بَأْسَ أَنْ تَأْخُذَهَا بِسَعْرِ يَوْمِهَا مَا لَمْ تَفْتَرِقَا وَبَيْنَكُمَا شَىْءٌ  

The tradition mentioned above has also been transmitted by Simak (b. Harb) with a different chain of narrators and to the same effect. The first version is more perfect. It does not mention the words "at the current rate".  

عَنْ سِمَاكٍ بِإِسْنَادِهِ وَمَعْنَاهُ وَالأَوَّلُ أَتَمُّ لَمْ يَذْكُرْ بِسِعْرِ يَوْمِهَا