Surah Fussilat 41:23

وَذَٰلِكُمْ ظَنُّكُمُ ٱلَّذِى ظَنَنتُم بِرَبِّكُمْ أَرْدَىٰكُمْ فَأَصْبَحْتُم مِّنَ ٱلْخَـٰسِرِينَ

And that was your assumption which you assumed about your Lord. It has brought you to ruin, and you have become among the losers."

Translation: Saheeh International

Tafsir

And that wa-dhālikum the subject supposition of yours zannukum substitutes for it which you supposed of your Lord alladhī zanantum bi-rabbikum a descriptive clause; the predicate is the following ardākum has ruined you that is it has brought about your destruction. So you have become among the losers’.

Excerpt from Tafsir al-Jalalayn, commentary on 41:23, via Quran.com. The reader has the full commentary and 9 more tafsirs.