﴿ وَقَالَ ٱلَّذِينَ كَفَرُوٓا۟ إِنْ هَٰذَآ إِلَّآ إِفْكٌ ٱفْتَرَىٰهُ وَأَعَانَهُۥ عَلَيْهِ قَوْمٌ ءَاخَرُونَ ۖ فَقَدْ جَآءُو ظُلْمًۭا وَزُورًۭا ﴾

“Moreover, those who are bent on denying the truth are wont to say, “This [Qur’an] is nothing but a lie, which he [himself] has devised with the help of other people, who thereupon have perverted the truth and brought a falsehood into being.””

Please check ayah 25:6 for complete tafsir.