( وَبَيْنَهُمَا حِجَابٌ ) (And between them will be a partition): There is a barrier between the people of Paradise and the people of Hell. In another verse, this barrier is described as:

 بَاطِنُهُ فِيهِ الرَّحْمَةُ وَظَاهِرُهُ مِن قِبَلِهِ الْعَذَابُ

(its interior containing mercy, but on the outside of it is torment) (Al-Hadid: 13)

So, it is a partition where on one side it contains suffering for the dwellers of Hell, and on the other side it contains mercy for the people of Paradise.

( وَعَلَى الْأَعْرَافِ رِجَالٌ) (and on [its] elevations are men): This is the first time that the third group is mentioned. The men on the heights, are those whose good deeds are equal to their bad deeds. The linguistic meaning of the Arabic word (Al-A’raaf) is: (a high place overlooking something). From this meaning originated the Arabic word for the caruncle of the rooster (‘Arf). (and on [its] elevations are men): means on the elevated parts of the partition, which is where it can be viewed from.

(يَعْرِفُونَ كُلًّا بِسِيمَاهُمْ) (who recognize all by their mark): They recognize each group by their features, as in the verse:

  وُجُوهٌ يَوْمَئِذٍ نَّاضِرَةٌ (22) إِلَىٰ رَبِّهَا نَاظِرَةٌ (23) وَوُجُوهٌ يَوْمَئِذٍ بَاسِرَةٌ (24) تَظُنُّ أَن يُفْعَلَ بِهَا فَاقِرَةٌ (25)

((22) [Some] faces, that Day, will be radiant (23) Looking at their Lord (24) And [some] faces, that Day, will be contorted (25) Expecting that there will be done to them [something] backbreaking) (Al-Qiyaama)

( وَنَادَوْا أَصْحَابَ الْجَنَّةِ أَن سَلَامٌ عَلَيْكُمْ ) (And they call out to the companions of Paradise, “Peace be upon you.”): The people on the heights turn to the inhabitants of Paradise and say: “Peace be upon you”, a greeting of faith, Islam, peace, and security.

( لَمْ يَدْخُلُوهَا وَهُمْ يَطْمَعُونَ) (They have not [yet] entered it, but they long intensely): At that point, the people on the heights had not entered Paradise but they hope to enter it.