It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that I used to sell camels in Jannat al-Baqi'. If I sold for dinars, I would take dirhams from the buyer, and if I sold for dirhams, I would take dinars from him. One day, to find out about this issue, I came to the Prophet (peace and blessings be upon him), and at that time I found him outside the house of Sayyidah Hafsa (may Allah be pleased with her). I asked the Prophet (peace and blessings be upon him) about this issue, and he said: "If it is at the price (agreed upon), then there is no harm in it."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 5559