The Barrier
In the holy Quran, the word ‘بَرْزَخٌ’ or ‘بَرْزَخًا’ means ‘barrier’ Sura e Al-Momin (23:100), Sura e Rehman (55: 20) and Sura Al-Furqan (25:53). It also means ‘barrier’ between the death and the Day of Reckoning.
الخصال أَبِي عَنْ سَعْدٍ عَنِ الْأَصْبَهَانِيِّ عَنِ الْمِنْقَرِيِّ عَنْ عَبْدِ الرَّزَّاقِ عَنْ مَعْمَرٍ عَنِ الزُّهْرِيِّ قَالَ قَالَ عَلِيُّ بْنُ الْحُسَيْنِ ع أَشَدُّ سَاعَاتِ ابْنِ آدَمَ ثَلَاثُ سَاعَاتٍ السَّاعَةُ الَّتِي يُعَايِنُ فِيهَا مَلَكَ الْمَوْتِ وَ السَّاعَةُ الَّتِي يَقُومُ فِيهَا مِنْ قَبْرِهِ وَ السَّاعَةُ الَّتِي يَقِفُ فِيهَا بَيْنَ يَدَيِ اللَّهِ تَبَارَكَ وَ تَعَالَى فَإِمَّا إِلَى الْجَنَّةِ وَ إِمَّا إِلَى النَّارِ
My father, from Sa’ad, from Al-Asbahany, from Al-Minqary, from Abdul Razaq, from Ma’mar, from Al-Zuhry who said,
Ali-asws Bin Al-Husayn-asws said: ‘The most difficult times of the son of Adam-as are three – the time in which he witnesses the Angel of death, and the time in which he would be standing from his grave, and the time in which he would pause in front of Allah-azwj, so either he would go to the Paradise or he would go to the Fire’.[1]
NB: For additional details, see for example https://hubeali.com/barzakh-what-happens-after-death/
[1] Bihar Al Anwaar – V 6, The book of Justice, S 2, Ch 6 H 19