Musnad Ahmad 30:3163

'Abd al-Rahman narrated to us, he said: Zuhayr ibn Muhammad narrated to us, he said: Musa ibn Abi Tamim narrated to me, from Sa'id ibn Yasar, from Abu Hurayrah, he said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "A dinar for a dinar, and a dirham for a dirham; there is no superiority between them." 'Abd al-Rahman said: And I read it to Malik, meaning this hadith.