Al-Baqara · 2:12

اَلَٓا اِنَّهُمْ هُمُ الْمُفْسِدُونَ وَلٰكِنْ لَا يَشْعُرُونَ

but really they are causing corruption, though they do not realize it

اَلَٓا
alā
Meaning
Nay, indeed
Part of speech
Opening particle (alā)
Role
Alerts the listener and asserts
Governor
opens the sentence
Case
Particle (mabnī)
Grammar
‘Nay! / Beware!’ — an opening particle that calls attention and strengthens what follows. It signals a firm correction of their claim.