Surah An-Nisa' (The Women), Verse 116

اِنَّ اللّٰهَ لَا یَغْفِرُ اَنْ یُّشْرَكَ بِهٖ وَیَغْفِرُ مَا دُوْنَ ذٰلِكَ لِمَنْ یَّشَآءُ وَمَنْ یُّشْرِكْ بِاللّٰهِ فَقَدْ ضَلَّ ضَلٰلًا بَعِیْدًا ۟

Innal laaha laa yaghfiru ai yushraka bihee wayaghfiru maa doona zaalika limai yashaaa'; wa mai yushrik billaahi faqad dalla dalaalam ba'eedaa

“Allah forgiveth not (The sin of) joining other gods with Him; but He forgiveth whom He pleaseth other sins than this: one who joins other gods with Allah, Hath strayed far, far away (from the right).”

Quran 4:116 (Yusuf Ali Translation)