Mishkat al-Masabih #2696

Abu Sa'id said that Bilal brought the Prophet some barni* dates, and when he asked him where he had got them he replied, "I had some inferior dates, so I sold two sa's of them for a sa." He said, "Ah, the very essence of usury, the very essence of usury. Do not do so, but when you wish to buy, sell the dates in a separate transaction, then buy with what you get." (Bukhari and Muslim.) * A type of dates of the best quality, sweet and luscious, red tinged with yellow.