Sales and Trade
Bukhari :: Book 3 :: Volume 34 :: Hadith 407
Narrated Ibn 'Umar:
Allah's Apostle forbade Al-Muzabana, i.e. to sell ungathered dates of one's garden for measured dried dates or fresh ungathered grapes for measured dried grapes; or standing crops for measured quantity of foodstuff. He forbade all such bargains.