﴿ حَتَّىٰٓ إِذَا بَلَغَ مَغْرِبَ ٱلشَّمْسِ وَجَدَهَا تَغْرُبُ فِى عَيْنٍ حَمِئَةٍۢ وَوَجَدَ عِندَهَا قَوْمًۭا ۗ قُلْنَا يَٰذَا ٱلْقَرْنَيْنِ إِمَّآ أَن تُعَذِّبَ وَإِمَّآ أَن تَتَّخِذَ فِيهِمْ حُسْنًۭا ﴾

“[And he marched westwards] till, when he came to the setting of the sun, it appeared to him that it was setting in a dark, turbid sea; and nearby he found a people [given to every kind of wrongdoing]. We said: "O thou Two-Horned One! Thou mayest either cause [them] to suffer or treat them with kindness!"”

until when he reached the setting of the sun the place where it sets he found it setting in a muddy spring ‘ayn hami’a a spring containing ham’a which is black clay its setting in a spring is described as seen from the perspective of the eye for otherwise it is far larger in size than this world; and he found by it that is by the spring a folk of disbelievers. We said ‘O Dhū’l-Qarnayn — by means of inspiration — either chastise the folk by slaying them or treat them kindly’ by merely taking them captive.