We performed the pilgrimage with Muawiya bin Abu Sufyan. When we arrived in Mecca, after he had prayed the noon prayer, he stood up and said, "The Messenger of Allah ﷺ said, 'The people of the two scriptures split in their religion into seventy-two sects, and this nation will split into seventy-three sects, meaning the followers of misguided desires. All of them will be in the Fire except one, which is the main body of the community. There will arise in my nation peoples through whom these desires will course just as rabies courses through the body of one bitten by a mad dog, leaving no vein or joint untouched.'By Allah, people of the Arabs, if you do not uphold what your Prophet ﷺ brought, then others are even less likely to uphold it."
حججنا مع معاوية بن أبي سفيان، فلما قدمنا مكة قام حين صلى صلاة الظهر، فقال إن رسول الله ﷺ قال: إن أهل الكتابين افترقوا في دينهم على وسبعين ثنتين ملة، وإن هذه الأمة ستفترق على ثلاث وسبعين ملة- يعني الأهواء- كلها في النار إلا واحدة، وهي الجماعة، وإنه سيخرج في أمتي أقوام تجارى بهم تلك الأهواء، كما يتجارى الكلب بصاحبه، لا يبقى منه عرق ولا مفصل إلا دخله، والله، يا معشر العرب، لئن لم تقوموا بما جاء به نبيكم ﷺ لغيركم من الناس أحرى أن لا يقوم به.
Ahmad (16937) narrated it, and this is his wording, as did Abu Dawud (4597), Darimi (2560), and Ibn Abu Asim in Sunnah (1, 2), and Hakim graded it sahih (1/128), all of them through routes from Safwan bin Amr, who said, Azhar bin Abdullah Harazi narrated to me, from Abu Amir Abdullah bin Lahi Hawzani, and he related it. Its chain is hasan because of Azhar bin Abdullah Harazi, for he is hasan al-hadith. Ibn Hajar also graded it hasan in Takhrij Ahadith Kashshaf (62).His saying "kalab" (rabies), with two open vowels, is a disease that afflicts a person from the bite of a mad dog. Similar in meaning is what has been narrated from Abdullah bin Amr bin As. Tirmidhi narrated it (2641), but it contains Abdul-Rahman bin Ziyad Ifriqi, who is daif.Khattabi said in Maalim Sunan, "This indicates that all these sects are not excluded from the religion, since the Prophet ﷺ made all of them part of his ummah. It also indicates that one who engages in interpretation is not excluded from the faith even if he errs in his interpretation." End of quote.I say, it is as he said. As for the saying "all of them are in the Fire except one," it means that these sects will not enter Paradise as an initial matter, just as they will not remain in the Fire eternally, unlike the saved sect, which will enter Paradise as an initial matter.As for the saying "my ummah will split into seventy-three sects," the intent is not a strict enumeration, but rather an indication of great number, since the strict enumeration does not correspond to reality.