فَمَا اسْطَاعُوا أَنْ يَظْهَرُوهُ وَمَا اسْتَطَاعُوا لَهُ نَقْبًا

Surah Al-Kahf : 97
So Gog and Magog were unable to pass over it, nor were they able [to effect] in it any penetration.

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