Barriers against evil and corruption

فَمَا ٱسْطَـٰعُوٓا۟ أَن يَظْهَرُوهُ وَمَا ٱسْتَطَـٰعُوا۟ لَهُۥ نَقْبًا

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