Yahya related to me from Malik from Abu'r-Rijal Muhammad ibn Abdar-Rahman ibn Haritha from his mother, Amra bint Abd ar-Rahman thatthe Messenger of Allah, may Allah bless him and grant him peace,forbade selling fruit until it was clear of blight. Malik said,"Selling fruit before it has begun to ripen is an uncertaintransaction (gharar) ."
USC-MSA web (English) reference: Book 31, Hadith 12
Arabic reference: Book 31, Hadith 1304