"The Messenger of Allah (ﷺ) forbade breaking the coins of the Muslims that are in circulation among them, without any necessary reason.”(1)
Sunan Ibn Majah Book 12, Hadith 127
← Previous Hadith "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.

Sunan Ibn Majah Book 12, Hadith 126 Next Hadith → Zaid, Abu 'Ayyash, the freed slave of Bani Zuhrah, told him that he asked Sa'd bin Abu Waqqas about buying wheat with barley. Sa'd said to him: "Which of them is better?" He said: "Wheat." He told him not to do that and said: "I heard the Messenger of Allah (ﷺ) being asked about buying fresh dates with dried dates, and he said: 'Do fresh dates decrease in weight when they become dry?' They said: 'Yes.' So he told them not to do that."

Sunan Ibn Majah Book 12, Hadith 128