Yahya related to me from Malik that he had heard from hisgrandfather, Malik ibn Abi Amir that Uthman ibn Affan said, "TheMessenger of Allah, may Allah bless him and grant him peace, said tome, 'Do not sell a dinar for two dinars nor a dirham for two dirhams.'"
USC-MSA web (English) reference: Book 31, Hadith 32
Arabic reference: Book 31, Hadith 1323