Sayyiduna Ibn Mas'ud (may Allah be pleased with him) says that there are two statements, one of which 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 a state in which he associates partners with Allah will enter Hell." And I say that whoever dies in a state in which he does not associate anyone with Allah will enter Paradise. And these prayers become an expiation for their intermediate times, provided that a person refrains from killing and fighting.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 3811