Sahih Bukhari Volume 3, Book 34, Hadith 2209

حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا إِسْمَاعِيلُ بْنُ جَعْفَرٍ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ ـ رضى الله عنه ـ أَنَّ النَّبِيَّ صلى الله عليه وسلم نَهَى عَنْ بَيْعِ ثَمَرِ التَّمْرِ حَتَّى تَزْهُوَ‏.‏ فَقُلْنَا لأَنَسٍ مَا زَهْوُهَا قَالَ تَحْمَرُّ وَتَصْفَرُّ، أَرَأَيْتَ إِنْ مَنَعَ اللَّهُ الثَّمَرَةَ بِمَ تَسْتَحِلُّ مَالَ أَخِيكَ

Narrated By Humaid : Anas said, "The Prophet forbade the selling of dates till they were almost ripe." We asked Anas, "What does 'almost ripe' mean?" He replied, "They get red and yellow. The Prophet added, 'If Allah destroyed the fruits present on the trees, what right would the seller have to take the money of his brother (somebody else)?'"