فَمَا اسْطَاعُوْٓا اَنْ يَّظْهَرُوْهُ وَمَا اسْتَطَاعُوْا لَهٗ نَقْبًا ( الكهف: ٩٧ )
Famas taa'ooo any yazharoohu wa mastataa'oo lahoo naqbaa (al-Kahf 18:97)
So they [i.e., Gog and Magog] were unable to pass over it, nor were they able [to effect] in it any penetration. (Al-Kahf  : 97)
1 Mufti Taqi Usmani
So they (Ya’jūj and Ma’jūj) were not able to climb it, nor were they able to make a hole in it.