"Indeed, We will bring down upon the people of this city a punishment from the sky because they have been defiantly disobedient"—meaning they commit shirk (polytheism).
﴿إِنَّا مُنْزِلُونَ عَلَى أَهْلِ هَذِهِ الْقَرْيَةِ رِجْزًا مِنَ السَّمَاءِ بِمَا كَانُوا يفسقون﴾ يشركُونَ