Ash-Shaykh Saalih al-Fawzaan hafidaho-Allah was asked the following question:
ما حال المجانين يوم القيامة يعني مصيرهم
“What will be the condition of the majnoon [i.e those who were totally insane] on the Day of Resurrection, meaning what will be their destination?”
Their destination will be to Allaah, The One who created them, I don’t know [what their condition will be].
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Ash-Shaykh Bin Baaz rahimahullah [full answer here] and Ash-Shaykh Muhammad bin Saalih al-Uthaymeen [full answer here] mentioned generally they will be tested and put to trial on the Day of Resurrection due to a hadith that comes in that meaning and some have mentioned another view. A safe stance is to just say Allaah knows best what their condition will be.
AbdulFattaah Bin Uthman