Those who wronged themselves substituted another saying for what they had been given to them. They were commanded to say: (Relieve us of our burdens), but they changed the words and said another inappropriate word indicating food which means (wheat).
( فَأَرْسَلْنَا عَلَيْهِمْ رِجْزًا مِّنَ السَّمَاءِ بِمَا كَانُوا يَظْلِمُونَ ) (So We sent upon them a punishment from the sky for the wrong that they were doing): The punishment sent upon them from the sky. The same Arabic word (punishment) is used in Surah Al-Muddaththir meaning (sins). Allah (swt) says:
وَالرُّجْزَ فَاهْجُرْ
(And uncleanliness avoid) (Al-Muddaththir: 5)
In this Surah, the word refers to punishment, which is the consequence of their sins due to their wrongdoing, arrogance, and violation of covenants.