It is disliked to make Nabidh by mixing dried dates and raisins
وَحَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا وَكِيعٌ، عَنْ إِسْمَاعِيلَ بْنِ مُسْلِمٍ الْعَبْدِيِّ، عَنْ أَبِي، الْمُتَوَكِّلِ النَّاجِيِّ عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " مَنْ شَرِبَ النَّبِيذَ مِنْكُمْ فَلْيَشْرَبْهُ زَبِيبًا فَرْدًا أَوْ تَمْرًا فَرْدًا أَوْ بُسْرًا فَرْدًا " .
Abu Sa'id al-Khudri reported Allah's Messenger (ﷺ) as saying: He who amongst you drinks Nabidh should drink that (prepared either from) grapes alone, or from dates alone, or from unripe dates alone (and not by mixing them with one another).