﴿ إِنَّ رَبَّهُم بِهِمْ يَوْمَئِذٍۢ لَّخَبِيرٌۢ ﴾

“that on that Day their Sustainer [will show that He] has always been fully aware of them?”

on that day their Lord will indeed be Aware of them Knower of them and will requite them for their disbelief the pronoun reverts to the plural because of the collective import of the term ‘man’; this sentence indicates the direct object of the verb ya‘lamu ‘does he not know’ that is to say ‘We will requite him at the time mentioned’; khabīrun ‘Aware’ is semantically connected to yawma’idhin ‘on that day’ even though in fact God is ever Aware because that is the Day of Requital.