وَصَدَّقَهُ الْمُؤْمِنُونَ عَلَى ذَلِكَ حَقًّا
The believers truly affirmed it as such.
Affirmation is more than reciting words: it is inward acceptance that the Qur’an is Allah’s speech and true revelation.
Faith therefore includes certainty regarding its divine origin and truth.