Anas (Allah be pleased with him) reported that Allah's Messenger (ﷺ) forbade the sale of the fruit of date-palms until it becomes mellow. We (some of the other narrators in the chain of transmitters) said:

What does the word" mellow" mean? He said: (There the fruit) turns red or yellow. Don't you see if Allah had checked (the growth of) fruits; then what for the wealth of your brother would be permissible for you?

حَدَّثَنَا يَحْيَى بْنُ أَيُّوبَ، وَقُتَيْبَةُ، وَعَلِيُّ بْنُ حُجْرٍ، قَالُوا حَدَّثَنَا إِسْمَاعِيلُ بْنُ جَعْفَرٍ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم نَهَى عَنْ بَيْعِ ثَمَرِ النَّخْلِ حَتَّى تَزْهُوَ ‏.‏ فَقُلْنَا لأَنَسٍ مَا زَهْوُهَا قَالَ تَحْمَرُّ وَتَصْفَرُّ ‏.‏ أَرَأَيْتَكَ إِنْ مَنَعَ اللَّهُ الثَّمَرَةَ بِمَ تَسْتَحِلُّ مَالَ أَخِيكَ .