An-Nisaa • BN-TAFSEER-IBN-E-KASEER
﴿ وَبِكُفْرِهِمْ وَقَوْلِهِمْ عَلَىٰ مَرْيَمَ بُهْتَٰنًا عَظِيمًۭا ﴾
“and for their refusal to acknowledge the truth, and the awesome calumny which they utter against Mary,”
Please check ayah 4:159 for complete tafsir.