Sahih Bukhari Volume 3, Book 34, Hadith Number 403.

Narated By Anas bin Malik : Allah’s Apostle forbade the sale of fruits till they are almost ripe. He was asked what is meant by ‘are almost ripe.’ He replied, “Till they become red.” Allah’s Apostle further said, “If Allah spoiled the fruits, what right would one have to take the money of one’s brother (i.e. other people)?”

Narrated Ibn Shihab: If somebody bought fruits before their benefit is evident and then the fruits were spoiled with blights, the loss would be suffered by the owner (not the buyer).

Narrated Salim bin ‘Abdullah from Ibn Umar: Allah’s Apostle said, “Do not sell or buy fruits before their benefit was evident and do not sell fresh fruits (dates) for dried dates.”