The man in charge of the dates brought the Messenger of Allah ﷺ some dates, and the Messenger did not recognize the type. He asked, "Where did you get these from?"The man replied, "We exchanged two saa of our dates for one saa of these."The Messenger of Allah ﷺ said, "You have committed riba."
حدثنا معتمر عن أبيه قال أنبأني أبو نضرة
أن صاحب التمر أتى رسول الله ﷺ بتمرة فأنكرها قال أنى لك هذا فقال اشترينا بصاعين من تمرنا صاعا فقال رسول الله ﷺ أربيتم
Its isnad is sahih, and Mutamir is Ibn Sulayman bin Tarkhan Taymi, both well-known and trustworthy. Muslim narrated the hadith 3/1216, no. 1594, in the book of sharecropping, on selling food for the same measure of food, and Abdul-Razzaq narrated it 8/33, no. 14191.