Sayyiduna Ibn Mas'ud (may Allah be pleased with him) narrates that the Prophet (peace and blessings of Allah be upon him) said: "Whoever dies in such a state that he does not associate anything with Allah, will enter Paradise." And I say that whoever dies in such a state that he associates anything with Allah, will enter Hell.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4038