﴿ أَفْتَرَىٰ عَلَى ٱللَّهِ كَذِبًا أَم بِهِۦ جِنَّةٌۢ ۗ بَلِ ٱلَّذِينَ لَا يُؤْمِنُونَ بِٱلْءَاخِرَةِ فِى ٱلْعَذَابِ وَٱلضَّلَٰلِ ٱلْبَعِيدِ ﴾

“Does he [knowingly] attribute his own lying inventions to God - or is he a madman?” Nay, [there is no madness in this Prophet -] but they who will not believe in the life to come are [bound to lose themselves] in suffering and in a profound aberration.”

Please check ayah 34:9 for complete tafsir.