The Book of Transactions
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَهَى عَنْ بَيْعِ الثَّمَرِ حَتَّى يَبْدُوَ صَلاَحُهَا نَهَى الْبَائِعَ وَالْمُبْتَاعَIbn 'Umar (Allah be pleased with them) reported that Allah's Messenger (ﷺ) forbade the sale of fruits until they were clearly in good condition, he forbade it both to the seller and to the buyer
From Sahih Muslim, whose reports the scholars accept as authentic.