Surat Al Kahf (85-86)

{فَأَتْبَعَ سَبَباً} (الكهف: 85)

85- He wanted to reach sunset, so he followed a way to deliver him.

{حَتَّى إِذَا بَلَغَ مَغْرِبَ الشَّمْسِ وَجَدَهَا تَغْرُبُ فِي عَيْنٍ حَمِئَةٍ وَوَجَدَ عِندَهَا قَوْماً قُلْنَا يَا ذَا الْقَرْنَيْنِ إِمَّا أَن تُعَذِّبَ وَإِمَّا أَن تَتَّخِذَ فِيهِمْ حُسْناً} (الكهف: 86)

86- Until Dhul-Qarnayn reached sunset in a fountain with black mud perhaps it is the mouth of the river, where mud is mixed with water, and everyone is seeing the sun sets in a place. When Dhul-Qarnayn reached the coast of the sea, he saw the sun sets in that place and found a nation at that fountain. So, We inspired Dhul-Qarnayn either to kill them if they do not accept Islam or to treat them nicely and call them to the truth and teach them guidance.