Surah Al-Baqarah 2:12

أَلَآ إِنَّهُمْ هُمُ ٱلْمُفْسِدُونَ وَلَـٰكِن لَّا يَشْعُرُونَ

Unquestionably, it is they who are the corrupters, but they perceive [it] not.

Translation: Saheeh International

Tafsir

Truly a-lā ‘truly’ is for alerting intended emphatically they are the agents of corruption but they perceive this not.

Excerpt from Tafsir al-Jalalayn, commentary on 2:12, via Quran.com. The reader has the full commentary and 9 more tafsirs.