Qur'an 4:48 · An-Nisaa

إِنَّ ٱللَّهَ لَا يَغْفِرُ أَن يُشْرَكَ بِهِۦ وَيَغْفِرُ مَا دُونَ ذَٰلِكَ لِمَن يَشَآءُ ۚ وَمَن يُشْرِكْ بِٱللَّهِ فَقَدِ ٱفْتَرَىٰٓ إِثْمًا عَظِيمًا

(48) Indeed, Allāh does not forgive association with Him, but He forgives what is less than that for whom He wills. And he who associates others with Allāh has certainly fabricated a tremendous sin.