Muwatta Malik, Book 31, Hadith 11 (USC-MSA) ⓘ

Yahya related to me from Malik from Humayd at-Tawil from Anas ibn Malik that the Messenger of Allah, may Allah bless him and grant him peace, 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, may Allah bless him and grant him peace, added, "Allah may prevent the fruit from maturing, so how can you take payment from your brother for it."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ حُمَيْدٍ الطَّوِيلِ، عَنْ أَنَسِ بْنِ مَالِكٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَهَى عَنْ بَيْعِ الثِّمَارِ حَتَّى تُزْهِيَ ‏.‏ فَقِيلَ لَهُ يَا رَسُولَ اللَّهِ وَمَا تُزْهِي فَقَالَ ‏"‏ حِينَ تَحْمَرُّ ‏"‏ ‏.‏ وَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ أَرَأَيْتَ إِذَا مَنَعَ اللَّهُ الثَّمَرَةَ فَبِمَ يَأْخُذُ أَحَدُكُمْ مَالَ أَخِيهِ ‏"‏ ‏.‏