«وَتَحْسَبُهُمْ أَيْقَاظًا وَهُمْ رُقُودٌ»
You would think them awake, although they are asleep.
ayqazan (awake) and ruqud (asleep) supply an immediate contrast. The wording highlights the gap between appearance and actuality, making the unusual condition especially vivid.
It exemplifies affirmative tibaq because the two opposed expressions are positively stated, not an affirmative and negative form of the same action.