It has been narrated by Abu Hurairah Radiyallahu Anh that the Prophet PBUH said:
“The Jews and Christians were divided into seventy-one or seventy-two religious sects, and this nation will be divided into seventy-three religious sects — all in Hell, except one, and that one is the one on which I and my Companions are today [i.e. following the Qur’an and the Prophet’s Sunnah (legal ways, orders, acts of worship, statements of the Prophet PBUH)].”
