Hadhrat Irbaadh (Radhiyallahu anhu) said: “One day Rasulullah (Sallallahu alayhe wasallam) after performing Salaat with us, faced us and delivered a most eloquent lecture which caused eyes to shed tears and hearts to quiver. Someone said:
“O Rasulullah (Sallallahu alayhe wasallam)! This appears to be a farewell address. What do you advise us? Rasulullah (Sallallahu alayhe wasallam) said: “I command you with Taqwa of Allah, and to hear and obey (the Ameer) even if he is a Habshi slave. Verily whoever among you lives after me will see severe discord. Therefore, impose on yourselves my Sunnah and the Sunnah of the rightly guided Khulafa. Hold on firmly to it (i.e. my Sunnah and their Sunnah).”
These Khulafa Al-Raashideen Al-Mahdiyyeen were Hadhrat Abu Bakr, Umar, Uthmaan and Ali (Radhiyallahu anhum). They were those noblest and greatest Sahaabah, the first three of whom the Shiahs proclaim kaafir/murtad.
It is most significant that Rasulullah (Sallallahu alayhe wasallam) equated the Sunnah of the Sahaabah to his own Sunnah. To follow this Sunnah is compulsory. Any path diverting from this Sunnah is dhalaal (satanic deviation) which leads to Jahannam.
Confirming the doom of all sects, Rasulullah (Sallallahu alayhe wasallam) said:
“Verily, this Ummah will split into 73 sects. All of them, except one, will be in the Fire”

This Naaji (Saved) sect according to Rasulullah (Sallallahu alayhe wasallam) is the Jama’ah (Group) who adheres to his Sunnah and the Sunnah of his Sahaabah. Therefore, understand that minus the Sahaabah there is no Islam.