Dhul-Qarnayn was a righteous king to whom God granted great power and knowledge of the earth's ways. He journeyed with his people across many lands, never wronging anyone, judging fairly and helping the weak wherever he went. His travels took him from the far west to the far east, and he met peoples of different tongues and customs, treating each with the justice or guidance they deserved.

Eventually Dhul-Qarnayn came to a people living between two mountains, who complained that a fierce people called Gog and Magog kept raiding their land. They offered him great wealth to build a wall between them. He refused the payment, saying, «What my Lord has given me is better,» and asked instead for their labor and strength.

He gathered blocks of iron between the two mountains until they rose level with the peaks, had fires lit beneath them until the iron glowed like embers, then poured molten copper over it, forming a wall so strong that no one could climb it or dig through it. Giving credit only to God, he said, «This is a mercy from my Lord,» and the once-frightened people lived on in safety because of his justice and wisdom.