In the Name of Allah, The Most Gracious, Ever Merciful.
Muslims who believe in the Messiah, Hadhrat Mirza Ghulam Ahmad Qadiani (as)
Holy Prophet (peace be upon him) among many of his prophecies has mentioned, in one hadith, a prophecy which many of us have seen fulfilled in our life time. More than 1400 years ago, our beloved master, Muhammad (peace be upon him) made a prophecy in the following words:
Abdullah bin Amar (RA) relates that the Holy Prophet (peace be upon him) said "Surely things will happen to my people as happened earlier to Israelites, they will resemble each other like one shoe in a pair resembles the other to the extent that if anyone among the Israelites has openly committed adultery to his mother there will be some who will do this in my Ummah as well, verily the Israelites were divided into 72 sections but my people will be divided into 73 sections, all of them will be in the fire except one." The companions asked, 'Who are they O Messenger of Allah,' Holy Prophet (peace be upon him) said, "They are those who will be like me and my companions."
In this hadith there are quite a few things to be noted. Firstly, it mentions the resemblance of Muslim Ummah with the Israelites (i.e. Jews). In another hadith  this resemblance is mentioned in the words that as among the Jews a prophet was raised in every century among Muslims a reformer will be raised and as among the Jews at the end of the chain of prophets a Messiah was raised a Messiah will be raised among Muslims. Among Jews there were 12 tribes each divided into six sects making a total of 72 sects at the time when the Messiah (i.e. Jesus, AS) was sent to Israelites (A full list of the Jewish sects at the time of Jesus, peace be upon him, is included in Appendix I). After the appearance of the Messiah among Jewish people the list of sects increased considerably. So while talking about 73 divisions among Muslims and taking into account the resemblances of Muslim Ummah to the Jewish people mentioned in both of the above tradition, it appears that these two ahadith relate to the time of the Promised Messiah (AS).