The Quran

وَبَينَهُما حِجابٌ ۚ وَعَلَى الأَعرافِ رِجالٌ يَعرِفونَ كُلًّا بِسيماهُم ۚ وَنادَوا أَصحابَ الجَنَّةِ أَن سَلامٌ عَلَيكُم ۚ لَم يَدخُلوها وَهُم يَطمَعونَ

Muhammad Asad

And between the two there will be a barrier.¹ And there will be persons who [in life] were endowed with the faculty of discernment [between right and wrong], recognizing each by its mark.² And they will call out unto the inmates of paradise, "Peace be upon you!"- not having entered it themselves, but longing [for it].

The word hijab denotes anything that intervenes as an obstacle between things or conceals one thing from another; it is used in both an abstract and a concrete sense.
The term al-a'raf (which gave to this surah its title) occurs in the Qur'an only twice - namely, in the above verse and in verse 48. It is the plural of 'urf, which primarily denotes "acknowledgement" or "discernment", and is also used to denote the highest, or most elevated, part of anything (because it is most easily discerned): for instance, the 'urf of a cock is the coxcomb, that of a horse its mane, and so forth. On the basis of this idiomatic usage, many commentators assume that the a'raf referred to here are "elevated places", like the heights of a wall or its ramparts, and identify it with the "barrier" (hijab) mentioned at the end of the preceding sentence. A far more likely interpretation, however, is forthcoming from the primary significance of the word 'urf and its plural a'raf: namely, "discernment" and "the faculty of discernment", respectively. This interpretation has been adopted by some of the great, early commentators of the Qur'an, like Al-Hasan al-Bagff and Az-Zajjaj, whose views Razi quotes with evident approval. They state emphatically that the expression 'ala 'l-a'raf is synonymous with 'ala ma'rifah, that is, "possessing knowledge" or "endowed with the faculty of discernment" (i.e., between right and wrong); and that the persons thus described are those who in their lifetime were able to discern between right and wrong ("recognizing each by its mark"), but did not definitely incline to either: in brief, the indifferent ones. Their lukewarm attitude has prevented them from doing either much good or much wrong - with the result that, as the next sentence shows, they deserve neither paradise nor hell. (Several Traditions to this effect are quoted by Tabari as well as by Ibn Kathir in their commentaries on this verse.) - The noun rijal (lit., "men") at the beginning of the next sentence as well as in verse 48 obviously denotes "persons" of both sexes.