( فَلَمَّا نَسُوا مَا ذُكِّرُوا بِهِ) (And when they forgot that by which they had been reminded): They were admonished and advised. Despite that, they turned away and forgot.
( أَنجَيْنَا الَّذِينَ يَنْهَوْنَ عَنِ السُّوءِ) (We saved those who had forbidden evil): The ones who were saved are those who were trying to prevent others from wrongdoings.
( وَأَخَذْنَا الَّذِينَ ظَلَمُوا بِعَذَابٍ بَئِيسٍ) (and seized those who wronged, with a wretched punishment): The wrongdoers were taken by severe and painful punishment.
( بِمَا كَانُوا يَفْسُقُونَ) (because they were defiantly disobeying): The reason for facing punishment is always disobedience and deviating from Allah’s (swt) commands. Allah (swt) sent Prophets and Messengers (PBUT) to deliver glad tidings and warnings. After that came reformers in every nation who advise people and prohibit evil. When people forget and go away from true religion, then punishment comes and the believers are saved by Allah’s (swt) Mercy. Thus, Allah (swt) does not wrong them, but it was the outcome of their actions that caused them the punishment.