29:48
وَمَا كُنتَ تَتْلُوا۟ مِن قَبْلِهِۦ مِن كِتَـٰبٍ وَلَا تَخُطُّهُۥ بِيَمِينِكَ ۖ إِذًا لَّٱرْتَابَ ٱلْمُبْطِلُونَ
wamā kunta tatlū min qablihi min kitābin walā takhuṭṭuhu biyamīnika idhan la-ir'tāba l-mub'ṭilūna
You never recited any Scripture before We revealed this one to you; you never wrote one down with your hand. If you had done so, those who follow falsehood might have had cause to doubt.
Neither did you (O Muhammad صلى الله عليه وسلم) read any book before it (this Qur’ân), nor did you write any book (whatsoever) with your right hand. In that case, indeed, the followers of falsehood might have doubted.