23:100 لَعَلِّىٓ أَعْمَلُ صَٰلِحًا فِيمَا تَرَكْتُ كَلَّآ إِنَّهَا كَلِمَةٌ هُوَ قَآئِلُهَا وَمِن وَرَآئِهِم بَرْزَخٌ إِلَىٰ يَوْمِ يُبْعَثُونَ
Haply I may do good in that which I have left. By no means! it is a (mere) word that he speaks; and before them is a barrier until the day they are raised.
25:53 وَهُوَ ٱلَّذِى مَرَجَ ٱلْبَحْرَيْنِ هَٰذَا عَذْبٌ فُرَاتٌ وَهَٰذَا مِلْحٌ أُجَاجٌ وَجَعَلَ بَيْنَهُمَا بَرْزَخًا وَحِجْرًا مَّحْجُورًا
And He it is Who has made two seas to flow freely, the one sweet that subdues thirst by its sweetness, and the other salt that burns by its saltness; and between the two He has made a barrier and inviolable obstruction.
Between them is a barrier which they cannot pass.