وَكَذَٰلِكَ جَعَلۡنَا فِي كُلِّ قَرۡيَةٍ أَكَٰبِرَ مُجۡرِمِيهَا لِيَمۡكُرُواْ فِيهَاۖ وَمَا يَمۡكُرُونَ إِلَّا بِأَنفُسِهِمۡ وَمَا يَشۡعُرُونَ ١٢٣
And thus We have placed within every city the greatest of its criminals to conspire therein. But they conspire not except against themselves, and they perceive [it] not.
Translation: Saheeh International (English)
Each word's meaning and sound
Just as what transpired with those leaders of Mecca who committed polytheism and barred others from the Way of Allah, He has placed leaders and influential people in every town who use various means and schemes to call towards the path of Satan and oppose the messengers and their followers. In reality, their scheming and planning will eventually only harm them, but they do realise this due to their ignorance and their following of desires.
Al-Mukhtasar in interpreting the Noble Quran