Abu Dawud
Commercial Transactions
Book Number: 016 / Hadith Number: 3353
Narated By Sa'd ibn AbuWaqqas : Zayd AbuAyyash asked Sa'd ibn AbuWaqqas about the sale of the soft and white kind of wheat for barley. Sa'd said: Which of them is better? He replied: Soft and white kind of wheat. So he forbade him from it and said: I heard the Apostle of Allah (pbuh) say, when he was asked about buying dry dates for fresh. The Apostle of Allah (pbuh) said: Are fresh dates diminished when they become dry? The (the people) replied: Yes. So the Apostle of Allah (pbuh) forbade that.