Yahya related to me from Malik from Humayd at-Tawil from Anas ibn Malik that the Messenger of Allah ﷺ forbade selling fruit until it had become mellow. He was asked, "Messenger ofAllah! What do you mean by become mellow?" He said, "When it becomes rosy." The Messenger of Allah ﷺ added, "Allah may prevent the fruit from maturing, so how can you take payment from your brother for it."
أَنَّ رَسُولَ اللَّهِ ﷺ نَهَى عَنْ بَيْعِ الثِّمَارِ حَتَّى تُزْهِيَ فَقِيلَ لَهُ يَا رَسُولَ اللَّهِ وَمَا تُزْهِي فَقَالَ حِينَ تَحْمَرُّ وَقَالَ رَسُولُ اللَّهِ ﷺ أَرَأَيْتَ إِذَا مَنَعَ اللَّهُ الثَّمَرَةَ فَبِمَ يَأْخُذُ أَحَدُكُمْ مَالَ أَخِيهِ