61جَنّاتِ عَدنٍ الَّتي وَعَدَ الرَّحمٰنُ عِبادَهُ بِالغَيبِ ۚ إِنَّهُ كانَ وَعدُهُ مَأتِيًّاMuhammad Asad[theirs will be the] gardens of perpetual bliss which the Most Gracious has promised unto His servants, in a realm which is beyond the reach of human perception:1 [and,] verily, His promise is ever sure of fulfilment!This lengthy paraphrase of the expression bi'l-ghayb gives, I think, the closest possible interpretation of the idea underlying it: namely, the prospect of a reality which is inconceivable by man in terms of his worldly experiences, and which can, therefore, only be hinted at by means of allegorical allusions. (See also the first clause of 2:3 and the corresponding note 3.)