﴿ فَٰكِهِينَ بِمَآ ءَاتَىٰهُمْ رَبُّهُمْ وَوَقَىٰهُمْ رَبُّهُمْ عَذَابَ ٱلْجَحِيمِ ﴾

“rejoicing in all that their Sustainer will have granted them: for their Sustainer will have warded off from them all suffering through the blazing fire.”

rejoicing delighting in what bi-mā relates to the verbal action their Lord has given them and that their Lord has shielded them from the chastisement of Hell-fire wa-waqāhum rabbuhum ‘adhāba’l-jahīmi is a supplement to ātāhum ‘what He has given them’ in other words rejoicing in their having been given this reward and shielded from Hell-fire.