It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever dies while setting up a rival to Allah will enter Hell. And the (five obligatory) prayers are an expiation for the (minor) sins between them, as long as major sins are avoided."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10378