Surah Al-Ahqaf 46:8

أَمْ يَقُولُونَ ٱفْتَرَىٰهُ ۖ قُلْ إِنِ ٱفْتَرَيْتُهُۥ فَلَا تَمْلِكُونَ لِى مِنَ ٱللَّهِ شَيْـًٔا ۖ هُوَ أَعْلَمُ بِمَا تُفِيضُونَ فِيهِ ۖ كَفَىٰ بِهِۦ شَهِيدًۢا بَيْنِى وَبَيْنَكُمْ ۖ وَهُوَ ٱلْغَفُورُ ٱلرَّحِيمُ

Or do they say, "He has invented it"? Say, "If I have invented it, you will not possess for me [the power of protection] from Allāh at all. He is most knowing of that in which you are involved. Sufficient is He as Witness between me and you, and He is the Forgiving, the Merciful."

Translation: Saheeh International

Tafsir

Or am has the significance of bal ‘nay but …’ and the rhetorical interrogative hamza of denial do they say ‘He has invented it?’ that is the Qur’ān. Say ‘If I have invented it hypothetically speaking still you would have no power to avail me against God that is to say against His chastisement in any way in other words …

Excerpt from Tafsir al-Jalalayn, commentary on 46:8, via Quran.com. The reader has the full commentary and 9 more tafsirs.