Surah Ar-Ra'd, Verse 43

وَيَقُولُ ٱلَّذِينَ كَفَرُواْ لَسۡتَ مُرۡسَلٗاۚ قُلۡ كَفَىٰ بِٱللَّهِ شَهِيدَۢا بَيۡنِي وَبَيۡنَكُمۡ وَمَنۡ عِندَهُۥ عِلۡمُ ٱلۡكِتَٰبِ٤٣

wayaqūlu alladhīna kafarū lasta mur'salan qul kafā bil-lahi shahīdan baynī wabaynakum waman ʿindahu ʿil'mu l-kitābi

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."