I heard the Messenger of Allah ﷺ being asked about buying dried dates in exchange for fresh dates. He asked those around him, "Do fresh dates decrease in weight when they dry?"They answered, "Yes."So he forbade that.Hannad narrated to us, Waki narrated to us, from Malik, from Abdullah bin Yazid, from Zayd Abu Ayyash, who said, "We asked Saad," and he mentioned something similar.
حدثنا قتيبة حدثنا مالك بن أنس عن عبد الله بن يزيد أن زيدا أبا عياش سأل سعدا عن البيضاء بالسلت فقال أيهما أفضل قال البيضاء فنهى عن ذلك
سمعت رسول الله ﷺ يسأل عن اشتراء التمر بالرطب فقال لمن حوله أينقص الرطب إذا يبس قالوا نعم فنهى عن ذلك حدثنا هناد حدثنا وكيع عن مالك عن عبد الله بن يزيد عن زيد أبي عياش قال سألنا سعدا فذكر نحوه
[Its isnad is hasan]. Abu Dawud narrated it in the Book of Sales, Chapter on Selling Fresh Dates for Dried Dates, no. 3359, and Ibn Majah, no. 2264, and Nasai, 7/298, 269, no. 4549, from the hadith of Malik through this route, and it is found in Muwatta, 2/624. Ibn Hibban graded it sahih (Mawarid), no. 657, as did Ibn Jarud, no. 657, and Hakim, 2/38, 39, and Dhahabi.