Sahih Muslim | Book 23 | Hadith Number 4907

Narrated by 'Abdullah b. Abu Qatada, on the authority of his father,
'Abdullah b. Abu Qatada, on the authority of his father, reported Allah's Apostle (may peace be upon him) forbidding the preparation of the mixture of ripe dates and unripe dates, and the mixture of grapes and dates, and that of nearly ripe dates and fresh dates but the Prophet said: Prepare the Nabidh from each one of them separately.