The Messenger of Allah ﷺ said, "The Jews split into seventy-one or seventy-two sects, and the Christians did the same, and my nation will split into seventy-three sects."
حدثنا الحسين بن حريث أبو عمار حدثنا الفضل بن موسى عن محمد بن عمرو عن أبي سلمة
أن رسول الله ﷺ قال تفرقت اليهود على إحدى وسبعين أو اثنتين وسبعين فرقة والنصارى مثل ذلك وتفترق أمتي على ثلاث وسبعين فرقة
[Its isnad is hasan]. Abu Dawud narrated it in the Book of Sunnah, chapter on explaining the sunnah, no. 4596, and Ibn Majah, no. 3991, from the hadith of Muhammad bin Amr, with the same wording. Ibn Hibban graded it sahih, no. 1834, as did Hakim, 1/128, saying it meets the criteria of Muslim, and Dhahabi agreed with him (!).There are also reports on this subject from Saad [Abd bin Humayd, no. 148], Abdullah bin Amr [coming up at 2641], and Awf bin Malik [Ibn Majah, no. 3992].