Sahih Muslim Book 10, Hadith Number 3680.

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

Zaid b. Thabit reported that Allah’s Messenger (may peace be upon him) give concession in case of ‘ariyya transactions according to which the members of the household give dry dates according to a measure and then eat fresh dates (in exchange for it)