Al-Muminoon • EN-TAFSIR-IBN-ABBAS
﴿ إِنْ هُوَ إِلَّا رَجُلٌ ٱفْتَرَىٰ عَلَى ٱللَّهِ كَذِبًۭا وَمَا نَحْنُ لَهُۥ بِمُؤْمِنِينَ ﴾
“He is nothing but a man who attributes his own lying inventions to God, and we are not going to believe him!””
(He is only a man) they mean the Messenger is only a man (who hath invented a lie about Allah) in that which he says. (We are not going to put faith in him) we are not going to believe what he says.