he did not like to exchange Dinars for Dirhams or Dirhams for Dinars.
Sunan an-Nasa'i Book 44, Hadith 136
← Previous Hadith "I used to sell gold for silver, or silver for gold. I came to the Messenger of Allah and told him about that, and he said: 'If you make a deal with your companion, d o not leave him when there is still any ambiguity (in the deal) between you."'

Sunan an-Nasa'i Book 44, Hadith 135 Next Hadith → he did not see anything wrong with parying Dirhams for Dinars.

Sunan an-Nasa'i Book 44, Hadith 137