It is narrated from Anas bin Malik (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) forbade selling fruits before they reach “zuhū.” So it was asked, O Messenger of Allah (peace and blessings be upon him)! What is zuhū? He replied: “Until they become red.” Then the Messenger of Allah (peace and blessings be upon him) said: “What do you think, if a calamity from the sky befalls the fruits by Allah’s command, then for what reason would you take your brother’s wealth?”
Hadith Referenceمسند الإمام الشافعي / كتاب البيوع / 1419
Hadith Takhrijاخرجه البخاري، البيوع، باب اذا باع الثمار قبل ان يبدو صلاحها..... الخ (2198)، (1488)، ومسلم، المساقاة، باب وضع الحوائج (1555)۔