Sahih Muslim Book 10, Hadith Number 3684.

Chapter : It is forbidden to sell fresh dates against dry dates, except in case of al-Araya.

Zaid b. Thabit (Allah be pleased with him) reported Allah’s Messenger (may peace be upon him) granting concession in case of ‘ariyya transactions and that implies selling of (dry dates for fresh dates) according to a measure.