The Cave - Al-Kahf

Then he followed (another) course.

Until when he reached the land of the rising of the sun, he found it rising on a people to whom We had given no shelter from It;

Even so! and We had a full knowledge of what he had.

Then he followed (another) course.

Until when he reached (a place) between the two mountains, he found on that side of them a people who could hardly understand a word.

They said: O Zulqarnain! surely Gog and Magog make mischief in the land. Shall we then pay you a tribute on condition that you should raise a barrier between us and them

He said: That in which my Lord has established me is better, therefore you only help me with workers, I will make a fortified barrier between you and them;

Bring me blocks of iron; until when he had filled up the space between the two mountain sides, he said: Blow, until when he had made it (as) fire, he said: Bring me molten brass which I may pour over it.