Al-An'am 6:123

Wakathalika jaAAalna feekulli qaryatin akabira mujrimeeha liyamkuroo feehawama yamkuroona illa bi-anfusihim wamayashAAuroon

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.

In a similar way, in every town We caused its chief sinners to commit mischief in it. And they do not commit mischief but against themselves, while they do not realize it.