Surah Al-Balad 90:12

وَمَآ أَدْرَىٰكَ مَا ٱلْعَقَبَةُ

And what can make you know what is [breaking through] the difficult pass?

Translation: Saheeh International

Tafsir

And what will show you what will make known to you what the obstacle is? that he is to surmount — intended to emphasise its enormity this statement is a parenthetical one. He explains the way to surmount it by saying

Excerpt from Tafsir al-Jalalayn, commentary on 90:12, via Quran.com. The reader has the full commentary and 9 more tafsirs.