The Prophet [SAW] forbade soaking dried dates and raisins, and dried dates and Al-Busr, and he said: "Soak raisins on their own, and dried dates on their own, and Al-Busr on their own." (Using translation from Nasāʾī 5571)   

أَنَّ النَّبِيَّ ﷺ نَهَى أَنْ يُنْبَذَ التَّمْرُ وَالزَّبِيبُ وَالتَّمْرُ وَالْبُسْرُ وَقَالَ «انْتَبِذُوا الزَّبِيبَ فَرْدًا وَالتَّمْرَ فَرْدًا وَالْبُسْرَ فَرْدًا»