And what will make you know what Sijjin is?
meaning, it is a great matter, an eternal prison, and a painful torment. Some have said that it is beneath the seventh earth.
It has been mentioned previously in the lengthy Hadith of Al-Bara' bin `Azib that the Prophet said,
يَقُول اللهُ عَزَّ وَجَلَّ فِي رُوحِ الْكَافِرِ اكْتُبُوا كِتَابَهُ فِي سِجِّينٍ وَسِجِّينٌ هِيَ تَحْتُ الاَْرْضِ السَّابِعَة
Allah says concerning the soul of the disbeliever, `Record his book in Sijjin.' And Sijjin is beneath the seventh earth."
it is known that the destination of the wicked people will be Hell, and it is the lowest of the low.
For Allah says,
ثُمَّ رَدَدْنَـهُ أَسْفَلَ سَـفِلِينَ إِلاَّ الَّذِينَ ءَامَنُواْ وَعَمِلُواْ الصَّـلِحَـتِ
Then We reduced him to the lowest of the low. Save those who believe and do righteous deeds. (95;5-6)
Here Allah says,
كَلَّ إِنَّ كِتَـبَ الْفُجَّارِ لَفِى سِجِّينٍ
وَمَأ أَدْرَاكَ مَا سِجِّينٌ
Nay! Truly, the Record of the wicked is in Sijjin. And what will make you know what Sijjin is? and it is full of hardship and misery.
Allah says,
وَإَذَا أُلْقُواْ مِنْهَا مَكَاناً ضَيِّقاً مُّقَرَّنِينَ دَعَوْاْ هُنَالِكَ ثُبُوراً
And when they shall be thrown into a narrow place thereof, chained together, they will exclaim therein for destruction. (25;13)
Then Allah says,
كِتَابٌ مَّرْقُومٌ