Surah 83. Al-Mutaffifin, Ayah 18

I.e., in contrast to the record of the wicked (see verse {7} above). As regards the term 'illiyyun, it is said to be the plural of 'illi or 'illiyyah ("loftiness") or, alternatively, a plural which has no singular (Qamus, Taj al-'Arus); in either case it is derived from the verb 'ala, which signifies "[something] was [or "became"] high" or "lofty" or - tropically - "exalted": thus in the well-known idiomatic phrase, huwa min 'illiyyat qawmihi, "he is among the [most] exalted of his people". In view of this derivation, the plural 'illiyyun has evidently the intensive connotation of "loftiness upon loftiness" (Taj al-'Arus) or "a mode most lofty".

 ’Illiyûn is an elevated place in Paradise.

'Illiyin: the oblique form of the nominative Illiyun, which occurs in the next verse. It is in contrast to the Sijjin which occurs in verse 7 above, where see n. 6213. Literally, it means the 'High Places'. Applying the reasoning parallel to that which we applied to Sijjin, we may interpret it as the Place where is kept the Register of the Righteous.