Punishment of the one who alters in religion
after the death of the Prophet
92) Narrated the Companions of the Prophet that the Prophet said: Some people of my Companions will arrive at the cistern of my Haud (pool) but they will be turned away (from it). So I will say: 0 Lord! They are my Companions. He will say: You don't know what heterodoxy they made after (your death), and reverted.
(This Haditb is sound and reported by Bukhari).
This Hadith asserts the role of the Sunnah (Prophetic traditions: sayings, deeds, approvals, and qualities of Muhammad Deviation from the Prophet's method is definitely going astray. One has to pray as he did, to invoke as he did, to sit as he did, to eat as he did, to smile as he did etc... Muhammad was the demonstrator who showed his Companions every thing even how to behave in the toilet, this means that he left for us a complete religion for all what one might need in his everyday life. So if you know the Sunnah, you have to apply it and if you do not know, you have to ask. Asking to know your religion is obligatory.