Abu Hurraira relates: I heard Allah's Apostle, peace and blessing of Allah be upon him, say, “Jews got divided into 71 or 72 sects and so did the Christians, and so it will happen to my people as well when they will be divided into 73 sects.”
This tradition can be found in the collections of Tirmidhī and Ibn Mājah. Imam al-Hakim calls it authentic and also adjudges it to be so on the criteria established by Imam Muslim. It is accepted as such by Sunnis as well as Shias.
Here the Holy Prophet compares the internal division of the latter day Muslims to the divisions among the Jews. In another narration he describes the similarity between the two people as two shoes from the same pair. Also, where he likens a part of his ummah to the Jews, he calls some others among them to have the messianic qualities of Jesus. Among the seventy three sects he calls one to be rightly-guided and makes it the duty of every Muslim to search for and identify that seventy third. Its distinguishing feature: , “they would be on the path and pattern of me and my companions.”
In another hadith he provides a distinction between the seventy two ‘hell-bound’ sects to the seventy third ‘safe’ sect calling it a jama'at, which means a united community. Clearly such a community cannot be conceived without the notion of an imam—a leader. When Huzaifa asked the Holy Prophet as to what are they to do in such times, he said, “join the community of Muslims which is led by an imam, and if you find no such community then detach yourself from the sects and stay detached even if you need to survive by eating roots of trees until death overtakes you.”
Another tradition states that in the time of schisms and divisions if you find a khalifa of God then attach yourself firmly to him even if you are tortured or are made to lose your belongings.
Today Muslims are divided into multitudinous sect, by various estimates the count of 72 sects was reached a long time ago and now has perhaps been exceeded. Nearly every sect lays claims to being the 73rd heaven-bound sect and, by implication, considers all others destined for the Fire. Who could blame them, this trophy remains the most coveted one. As it happens, each of these sects calls the others kafir, which is expected, yet in one matter they are curiously united. They have taken a united position against one particular community of Muslims. Seventy-two have grouped together declaring themselves heavenly while declaring the Ahmadiyya