The traditions are classified in terms of the number of reporters or narrators in either mutawatir or wahid. The term mutawatir comes from the root word 'watr" which means "one".  Mutawatir literally means for things to come one after another, without any interval between them as the Holy Quran says:
"ثُمَّ أَرْسَلْنَا رُسُلَنَا تَتْرَا[1]
"Then We sent Our messengers one after another."
The word 'tatra' in the verse means in succession or one after another.[2]  However, a mutawatir narration in the technical meaning refers to a narration that has been reported by a group of narrators in every stage or level of report that one can be definite that they haven’t all agreed on forging and lying. Any hadith with such a trait will surely make its reader certain that it is true.[3]
Although there are few mutawatir traditions, they are generally indicative of an important report or event such as the tradition of Ghadir Khum which has been reported only in the sahaba levels by more than one hundred people.
Types of Mutawatir report:
Mutawatir reports are divided into lafdhi and ma'anawi.  Lafdhi indicates that the mutawatir hadith is one that has been narrated many times with the same phrases and words.[4] An instance of lafdhi mutawatir is the following hadith:
"من كذب عليّ متعمّدا فليتبوّء مقعده من النار."[5]
A great many companions, forty to sixty of them, have reported this tradition.[6]
Ma’anawi signifies that a certain message is a common one amongst several hadiths. The significations and denotations of the hadith is the same.[7]
There is another classification for a mutawatir report and that is tafsili and ijmali. The former includes lafdhi and ma'anawi tawatur. As for ijmali tawatur, when one knows that one of several hadiths on a certain topic has surely been issued from one of the infallibles, without knowing exactly which one, it is called ijmali tawatur. In this kind of tawatur, one rest assured that out of all the reports, one is definitely from the imam such as the reports narrated about the authority of khabar wahid (report by single person).[8]
As for khabar wahid, it is a hadith that has been narrated by one or several narrators which doesn’t cause anyone to be certain about the message it conveys, unless other signs are found that might help in trusting it. Thus, it is a report whose reporters in all levels have not attained the extent of tawatur.[9] Such narrations do not cause anyone to be about the message it conveys unless there are other indications corroborating them and which make one certain that they are authoritative. Hence, if a tradition, at certain stages reaches the level of tawatur, but at another stage it does not qualify for tawatur, it is not considered to be mutawatir but it will khabar wahid.
When it comes to the number of narrators, Shiite scholars have not determined or defined it. In fact, the criterion is whether or not it causes anyone to be certain about the message.  Any report whose narrators at every level reaches the extent where it causes one to become certain that it has been issued from the imam.  On the other hand, it is impossible that so many reporters should have agreed to lie or fabricate a tradition.  From this perspective, according to Shiite scholars there is not any difference between lafdhi, ma'anawi and ijmali mutawatir.
As for Sunni scholars' view about mutawatir report, they have fixed the number of narrators narrating the traditions but still there are different sayings:
1.  Qadhi Abi Bakr Baqlani is of the view there should be at least four narrators.
2. Astakhari is of the view that there must be at least ten people to narrate.
3. Some other Sunni scholars are of the view that the number of narrators should be at least 12 people.
4. Abu Huzayl Ilaf is of the view that there should be at least 20 narrators.
5. Another view is that there should be at least 40 narrators.
6. Another group of scholars believe that the number of narrators should reach 70.
7. The last view is that the number of narrators must be 313 (as was the number of the companions in the Battle of Badr).[10]

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