Sahih Muslim Book 23, Hadith Number 4897.

Chapter : It is not approved to prepare Nabidh by mixing dry dates and grapes.

Jabir b. ‘Abdullah al-Ansari reported that Allah’s Messenger (may peace be upon him) prohibited the (preparation of) Nabidh by mixing together fresh dates and grapes, and he prohibited the preparation of Nabidh by mixing the fresh dates and unripe dates together.