Sahih Muslim Book 10, Hadith Number 3687.

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

Bashair b. Yasir reported on the authority of some of the Companions of Allah’s Messenger (may peace be upon him) among the members of his family among whom one was Sahl b. Abu Hathma that Allah’s Messenger (may peace be upon him) forbade buying of fresh dates against dry dates and that it is Riba and this is Muzabana, but he made an exemption of ‘ariyya (donations) of a tree or two in which case the members of a family sell dry dates and buy fresh dates for eating them.