Abu Sa'id reported that Allah's Apostle ﷺ prohibited that fresh dates and grapes be mixed together and that fresh dates and unripe dates be mixed together. (Using translation from Muslim 1987a)   

«نَهَى رَسُولُ اللهِ ﷺ عَنِ الْجَرِّ أَنْ يُنْبَذَ فِيهِ وَعَنِ التَّمْرِ وَالْبُسْرِ أَنْ يُخْلَطَ بَيْنَهُمَا وَعَنِ التَّمْرِ وَالزَّبِيبِ أَنْ يُخْلَطَ بَيْنَهُمَا»  

"The Messenger of Allah [SAW] forbade mixing dried dates and raisins, and dried dates and Al-Busr." (Using translation from Nasāʾī 5559)  

«نَهَى رَسُولُ اللهِ ﷺ عَنْ خَلِيطِ التَّمْرِ وَالزَّبِيبِ وَعَنِ التَّمْرِ وَالْبُسْرِ»