Qur'an 4:48

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

“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.”

An-Nisaa 4:48 · Saheeh International