Quran 6:123 from Surah Al-An'aam on Divine Marvels.
وَكَذَٰلِكَ جَعَلۡنَا فِي كُلِّ قَرۡيَةٍ أَكَٰبِرَ مُجۡرِمِيهَا لِيَمۡكُرُواْ فِيهَاۖ وَمَا يَمۡكُرُونَ إِلَّا بِأَنفُسِهِمۡ وَمَا يَشۡعُرُونَ
English translation: And thus We placed in every city greatest (of) its criminals so that they plot therein And not they plot except against themselves and not they perceive
Transliteration: wakadhalika ja'alna fi kulli qaryatin akabira muj'rimiha liyamkuru fiha wama yamkuruna illa bi-anfusihim wama yash'uruna