preservation of deeds

۞ يَسْتَبْشِرُونَ بِنِعْمَةٍ مِّنَ ٱللَّهِ وَفَضْلٍ وَأَنَّ ٱللَّهَ لَا يُضِيعُ أَجْرَ ٱلْمُؤْمِنِينَ

They receive good tidings of favor from Allāh and bounty and [of the fact] that Allāh does not allow the reward of believers to be lost -

كِتَـٰبٌ مَّرْقُومٌ

It is [their destination recorded in] a register inscribed.