﴿ مَّا يَلْفِظُ مِن قَوْلٍ إِلَّا لَدَيْهِ رَقِيبٌ عَتِيدٌۭ ﴾

“not even a word can he utter but there is a watcher with him, ever-present.”

he does not utter a word but that there is beside him a watcher a guardian who is ready present both raqībun ‘watcher’ and ‘atīdun ‘ready’ are meant to indicate the dual.