Surah Ar-Ra'd, ayah 43

وَيَقُولُ ٱلَّذِينَ كَفَرُواْ لَسۡتَ مُرۡسَلٗاۚ قُلۡ كَفَىٰ بِٱللَّهِ شَهِيدَۢا بَيۡنِي وَبَيۡنَكُمۡ وَمَنۡ عِندَهُۥ عِلۡمُ ٱلۡكِتَٰبِ ٤٣

Wayaqūlul-ladhīna kafarū lasta mursalan qul kafā billāhi shahīdā baynī wabaynakum waman 'indahū 'ilmul-kitāb

And those who have disbelieved say, "You are not a messenger." Say, [O Muḥammad], "Sufficient is Allāh as Witness between me and you, and [the witness of] whoever has knowledge of the Scripture."⁶⁴⁶