In The Name of Allaah, The Most Merciful, The Bestower of Mercy.

Imaam Sahl Bin Abdillaah At-Tustaree [rahimahullaah] said: “Safety is found in three things: A lawful means of living, fulfilling obligatory deeds and following the Messenger [sallal-laahu-alayhi-wasallam]”. [source: Tafseer Qur’tubee:2/208]

Imaam Ibn Rajab [rahimahullaah] said: The Messenger [salallal-laahu-alayhi-wasallam] said: “The one who lives long [after me] will see a lot of differences, so beware of the newly invented matters [in the religion] because it is misguidance.  So whoever amongst you reaches that [time of differing], then upon him is to adhere to my Sunnah and the Sunnah of the Rightly Guided Khulafaa [i.e. Abu Bakr, Umar, Uthmaan and Ali], and bite onto it with the molars [i.e. cling to it firmly]”. [Abu Dawud 4607; Ahmad 4/126; Tirmidhee 2676]

He [sallal-laahu – alayhi – wasallam] commanded [us] that during splitting and differing, one should adhere to his Sunnah and the Sunnah of the rightly guided khulafaa after him. The Sunnah is the path that is to be adhered to, and that includes adhering to what he [sallal-laahu-alayhi wasallam] and his rightly guided khulafaa were upon with regards to creed, actions and statements.  This is the complete Sunnah.  [Jaami-ul uloom wal hikam page:249]