An-Nisa · 4:48

48. Allah does not forgive that anything from His creation should be associated to Him. Besides this and disbelief, He pardons the disobedience of whomever He wills, out of His bounty. Or He punishes those He wills among them according to their disobedience, out of His perfect justice. Whoever worships others next to Allah has committed a terrible sin, which is not forgiven if someone dies still doing it.