فَلَا يُزَادُ فِي ذَلِكَ الْعَدَدِ وَلَا يُنْقَصُ مِنْهُ
There will be no increase in that number and no reduction from it.
This expresses the certainty of Allah’s eternal knowledge. His knowledge of each person's final outcome contains no error, deficiency, or revision implying that the earlier knowledge had been incomplete.