Musannaf Ibn Abi Shayba 13:2140

Abu Bakr narrated to us, he said: Yazid bin Harun narrated to us, he said: Hushaym narrated to us, from al-Hasan: That he did not see any harm in two men entering into a partnership, where one brings dinars and the other brings dirhams. And he said: "Dinars are all of the same kind. So when they wish to separate, the owner of the dinars takes the dinars, and the owner of the dirhams takes the dirhams, then they divide the profit." Hisham said: And Muhammad used to prefer that it be dirhams with dirhams, and dinars with dinars.