Jabir told that a slave came and swore allegiance to the Prophet promising to emigrate, but he did not know that he was a slave. When his master came in search of him the Prophet said to him, ‘Sell him to me," and he bought him for two black slaves. Afterwards he never took an oath of allegiance from anyone without asking him whether he was a slave or free.
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.
Abu Sa'id and Abu Huraira told that God’s Messenger appointed a man over Khaibar and he brought him dates of a very fine quality. He asked him whether all the dates of Khaibar were like that, and he replied, “I swear by God that they are certainly not, Messenger of God. We take a sa‘ of this kind for two, and two for three." So he said, "Do not do so. Sell the lot for dirhams, then buy the very fine dates for dirhams." He said that it was the same when things were sold by weight.
