This Ummah will split into 73 sects. That is what Rasoolullaah صلى الله عليه وسلم informed us.
Now, the `Ulamaa of Arabic have mentioned something with regards to the usage of the number 70 in Arabic, and that is: The number 70 can be used in one of two ways:
I have always regarded as literal, even the hadiths are evident of that.
The famous hadeeth about the ummah splitting into seventy-three sects bears witness to that.
It was narrated from Mu’aawiyah ibn Abi Sufyaan (may Allaah be pleased with him) that he said: The Messenger of Allaah (peace and blessings of Allaah be upon him) stood among us and said: “Those who came before you of the people of the Book split into seventy-two sects, and this ummah will split into seventy-three: seventy-two in Hell and one in Paradise, and that is the jamaa’ah (main body of Muslims).”
Narrated by Abu Dawood (4597) and others; classed as saheeh by al-Haakim (1/128), who said: it is an important hadeeth that represents a basic principle. It was classed as hasan by Ibn Hajar in
Takhreej al-Kashshaaf (63). It was classed as saheeh by Ibn Taymiyah in
Majmoo’ al-Fataawa (3/345), al-Shaatibi in
al-I’tisaam (1/430), and al-‘Iraaqi in
Takhreej al-Ihya’ (9/133). It is mentioned frequently and often quoted as evidence by the scholars in the books of Sunnah, and it was narrated from a number of the Sahaabah via many isnaads, most of the soundest of which specify the number of sects as being seventy-three.
Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) said:
Similarly, with the other seventy-two groups, those that are hypocrites are inwardly kaafirs, and those that are not hypocrites but rather believe inwardly in Allaah and His Messenger are not inwardly kaafirs, even though they are mistaken in their interpretations, regardless of what that mistake may be. Some of them may have some of the branches of hypocrisy, or they may not have the kind of hypocrisy that dooms a man to the lowest depths of Hell.
The one who says that each of the seventy-two sects is guilty of kufr that puts one beyond the pale of Islam is going against the Qur’aan and Sunnah and the consensus of the Sahaabah (may Allaah be pleased with them all), and the consensus of the four imams and others. None of them regarded any of the seventy-two sects as kaafirs, rather they regard one another as kaafirs.
Majmoo’ al-Fataawa (7/218).
This does not mean that every sect that calls itself Muslim is actually Muslim, rather they may be kaafirs and apostates, such as the extreme Raafidis, the extreme Sufis and the baatini sects such as the Druze, Nusayris and others. These are all beyond the pale of Islam and are not regarded as being among the sects mentioned in the hadeeth.
https://islamqa.info/en/90112