The Prophet ﷺ forbade the mixing of ripe and unripe dates and also the mixing of dates and raisins (for preparing a syrup) but the syrup of each kind of fruit should be prepared separately. ( One may have such drinks as long as it is fresh ) (Using translation from Bukhārī 5602)  

«نَهَى رَسُولُ اللهِ ﷺ أَنْ يُجْمَعَ بَيْنَ التَّمْرِ وَالزَّبِيبِ»