Verse 48

وَمَا كُنتَ تَتْلُوا۟ مِن قَبْلِهِۦ مِن كِتَـٰبٍ وَلَا تَخُطُّهُۥ بِيَمِينِكَ إِذًا لَّٱرْتَابَ ٱلْمُبْطِلُونَ

You never recited any scripture before this, and nor did you write one with your hand, otherwise the falsifiers would have had a lot of doubt.