Sahih Al Bukhari Hadith Number 1486

Narrated Ibn `Umar: The Prophet (peace be upon him) had forbidden the sale of dates till they were good (ripe), and when it was asked what it meant, the Prophet (peace be upon him) said, “Till there is no danger of blight.”

24  Obligatory Charity Tax (Zakat)
Hadith number 1486
Volume no 2
Chapter: 58 (Whoever sold his fruits, trees, land or crops and gave Zakat from some other property)