They were forbidden to exchange currency, and two men among them traced this back to the Prophet of Allah ﷺ.
حدثنا محمد بن جعفر حدثنا سعيد أن محمدا حدث أن ذكوان أبا صالح حدث
أنهم نهوا عن الصرف ورفعه رجلان منهم إلى نبي الله ﷺ
Its isnad is sahih. There is some discussion regarding Muhammad bin Jafar's hearing from Saeed bin Abu Aruba, but it is not harmful. Muhammad is Ibn Sirin. The hadith was narrated by Nasai, 7/277, no. 4565, and Ibn Majah, 2/759, no. 2258.