Sayyiduna Ibn Mas'ud (may Allah be pleased with him) says that there are two statements: one I heard from the Prophet (peace and blessings of Allah be upon him), and the other I say from myself. The Prophet (peace and blessings of Allah be upon him) said: "Whoever dies in such a state that he does not associate anyone with Allah, he will enter Paradise." And I say that whoever dies in such a state that he associates someone with Allah, he will enter Hell.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 3625
Hadith Gradingحکم دارالسلام:رجاله ثقات إلا أن فيه قلبا، فقد جعل المرفوع موقوفا، والموقوف مرفوعا، خ: 1238، م: 92