Musnad Ahmad 31:604

Hisham ibn Sa'id narrated to us, he said: Mu'awiyah ibn Abi Salam al-Habashi narrated to us, he said: I heard Yahya ibn Abi Kathir saying: I heard 'Uqbah ibn 'Abd al-Ghafir saying: I heard Abu Sa'id al-Khudri saying: Bilal came to the Messenger of Allah (peace and blessings of Allah be upon him) with dates. He said: "Where did you get this from?" He said: "I had some inferior dates, so I sold them for this." The Prophet (peace and blessings of Allah be upon him) said: "Oh, the essence of usury! The essence of usury! Do not go near it. But sell your dates for whatever you wish, then buy with it whatever you desire."