Sahih Bukhari
Sales and Trade
Volume: 003 / Book Number: 034 / Hadith Number: 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.