Tafseer Ibn Kathir of AL HAJJ [7]

وَأَنَّ السَّاعَةَ آتِيَةٌ لَّا رَيْبَ فِيهَا وَأَنَّ اللَّهَ يَبْعَثُ مَن فِي الْقُبُورِ

And [that they may know] that the Hour is coming - no doubt about it - and that Allah will resurrect those in the graves.