He said: [and mentioned that he commanded the Muslims to unite in their religion and forbade them from dividing in it, and this principle is further clarified by what the sunnah has brought, which is truly astonishing in this regard]. The astonishing matter is that the ummah will divide into seventy-three sects, as the Prophet (ṣallá Allāhu ʿalayhi wa-sallam) said: "The Jews divided into seventy-one sects, and the Christians divided into seventy-two sects, and this ummah will divide into seventy-three sects, all of them in the Fire except one." Therefore, it is incumbent upon the believer to strive to be among this one sect that the Messenger of Allāh (ṣallá Allāhu ʿalayhi wa-sallam) gave glad tidings of salvation, and its description is found in the sunnah of the Messenger of Allāh (ṣallá Allāhu ʿalayhi wa-sallam); for in the narration of al-Tirmidhī, when he was asked about the saved sect, he said: "They are those who are upon what I am upon and my Companions," and in another narration, he said: "It is the community," and the community are those united upon the Book of Allāh and the sunnah of His Messenger (ṣallá Allāhu ʿalayhi wa-sallam).