Surat Al-'Aĥqāf - سورة الأحقاف

أَمْ يَقُولُونَ افْتَرَاهُ ۖ قُلْ إِنِ افْتَرَيْتُهُ فَلَا تَمْلِكُونَ لِي مِنَ اللَّهِ شَيْئًا ۖ هُوَ أَعْلَمُ بِمَا تُفِيضُونَ فِيهِ ۖ كَفَىٰ بِهِ شَهِيدًا بَيْنِي وَبَيْنَكُمْ ۖ وَهُوَ الْغَفُورُ الرَّحِيمُ

Muhsin Khan: Or say they: "He (Muhammad SAW) has fabricated it." Say: "If I have fabricated it, still you have no power to support me against Allah. He knows best of what you say among yourselves concerning it (i.e. this Quran)! Sufficient is He for a witness between me and you! And He is the Oft-Forgiving, the Most Merciful."