Al-Kahf 18:95

ثُمَّ أَتْبَعَ سَبَبًا

Then he followed a way

حَتَّىٰ إِذَا بَلَغَ بَيْنَ السَّدَّيْنِ وَجَدَ مِن دُونِهِمَا قَوْمًا لَّا يَكَادُونَ يَفْقَهُونَ قَوْلًا

Until, when he reached [a pass] between two mountains, he found beside them a people who could hardly understand [his] speech.

قَالُوا يَا ذَا الْقَرْنَيْنِ إِنَّ يَأْجُوجَ وَمَأْجُوجَ مُفْسِدُونَ فِي الْأَرْضِ فَهَلْ نَجْعَلُ لَكَ خَرْجًا عَلَىٰ أَن تَجْعَلَ بَيْنَنَا وَبَيْنَهُمْ سَدًّا

They said, "O Dhul-Qarnayn, indeed Gog and Magog are [great] corrupters in the land. So may we assign for you an expenditure that you might make between us and them a barrier?"

آتُونِي زُبَرَ الْحَدِيدِ ۖ حَتَّىٰ إِذَا سَاوَىٰ بَيْنَ الصَّدَفَيْنِ قَالَ انفُخُوا ۖ حَتَّىٰ إِذَا جَعَلَهُ نَارًا قَالَ آتُونِي أُفْرِغْ عَلَيْهِ قِطْرًا

Bring me sheets of iron" - until, when he had leveled [them] between the two mountain walls, he said, "Blow [with bellows]," until when he had made it [like] fire, he said, "Bring me, that I may pour over it molten copper."

فَمَا اسْطَاعُوا أَن يَظْهَرُوهُ وَمَا اسْتَطَاعُوا لَهُ نَقْبًا

So Gog and Magog were unable to pass over it, nor were they able [to effect] in it any penetration.

قَالَ هَـٰذَا رَحْمَةٌ مِّن رَّبِّي ۖ فَإِذَا جَاءَ وَعْدُ رَبِّي جَعَلَهُ دَكَّاءَ ۖ وَكَانَ وَعْدُ رَبِّي حَقًّا

[Dhul-Qarnayn] said, "This is a mercy from my Lord; but when the promise of my Lord comes, He will make it level, and ever is the promise of my Lord true."