ذَٰلِكَ بِمَا قَدَّمَتْ أَيْدِيكُمْ وَأَنَّ ٱللَّهَ لَيْسَ بِظَلَّٰمٍۢ لِّلْعَبِيدِ
That is for what your hands have put forth [of evil] and because Allah is not ever unjust to His servants."
That chastisement is for what your hands have sent before you — He refers to this their actions exclusively with these hands because most actions are accomplished with them — and know that God is never unjust to His servants’ such that he would punish them for no sin.