The seven modes of recitation are mutawaatir and it is not permissible to cast aspersions on them
Question

We say that the seven modes of recitation are mutawaatir and are divine revelation, but how can that be when the term mutawaatir did not appear before Ibn Mujaahid, who was the seventh of seven?
[A mutawaatir hadith is one that was transmitted by so many narrators at each stage of its isnaad (chain of transmission) that it is inconceivable that they could all have agreed on a lie.]
Praise be to Allah.Firstly:
The majority of scholars of recitation and usool are of the view that the seven modes of recitation are mutawaatir going back to the Prophet (blessings and peace of Allah be upon him). Some of them differed concerning that, such as Abu Shaamah – according to one of his views – and at-Tawfi and ash-Shawkaani. However the correct view concerning that is the view of the majority; that is the right view which must be adopted.
Shihaab ad-Deen ad-Dimyaati (may Allah have mercy on him) said:
Taaj al-A’immah as-Subki – who is Taaj ad-Deen ‘Abd al-Wahhaab as-Subki – said in his fatwas:
The seven modes of recitation to which ash-Shaatibi referred, to the exclusion of others, and the three others – namely the recitation of Abu Ja‘far, the recitation of Ya‘qoob and the recitation of Khalaf – are mutawaatir and well-known, and it is an established fact in the religion that they were revealed to the Messenger of Allah. No one would stubbornly disagree with that except one who is ignorant. They are not only regarded as mutawaatir by those who know these ten modes of recitation; rather they are regarded as mutawaatir by every Muslim who says “I bear witness that there is no god but Allah and I bear witness that Muhammad is the Messenger of Allah,” even if he is rough and uneducated and has not memorised even one letter of the Qur’an.
He said: We could elaborate on the proof and evidence, but we do not have room to discuss this matter at length here. However, what is expected of every Muslim, and what he should do is to accept before Allah, may He be exalted, and be certain that what we have mentioned is mutawaatir and is known for certain, and there is no room for doubt or uncertainty about it.
Conclusion:
The seven modes of recitation are mutawaatir according to consensus, as are the three others: the recitations of Abu Ja‘far, Ya‘qoob and Khalaf, according to the more correct view. In fact the correct, favoured view, which is what we learned from most of our shaykhs, is that the recitations of the other four – Ibn Muhaysin, al-Yazeedi, al-Hasan and al-A‘mash, are odd (shaadhdh), according to scholarly consensus.
An-Nawawi (may Allah have mercy on him) said:
Our companions and others said:
It is permissible to recite, in prayer and otherwise, according to any of the seven modes of recitation, but it is not permissible to recite, in prayer or otherwise, according to an odd mode of recitation, because that is not Qur’an. Qur’an can only be proven by means of mutawaatir reports, and each of the seven modes of recitation is mutawaatir. This is the correct view which one must accept, and whoever says otherwise is wrong or ignorant.
End quote from al-Majmoo‘ (3/392)
Ibn an-Najjaar al-Fatoohi (may Allah have mercy on him) said:
The seven modes of recitation are mutawaatir according to the four imams and other leading Sunni scholars. This was narrated by as-Sarakhsi, who was one of the companions of ash-Shaafa‘i, in Kitaab as-Sawm in al-Ghaayah. He said: The Mu‘tazilah said: (The modes of recitation are transmitted via) aahaad reports.
[An aahaad hadith is one of which the narrators at each stage of the isnaad are too few for it to be regarded as mutawaatir.]
End quote from Sharh al-Kawkab al-Muneer (2/127)
Az-Zarqaani (may Allah have mercy on him) said:
The fact that is supported by evidence is that the ten modes of recitation are all mutawaatir. This is the view of the scholars of usool and of recitation, such as Ibn as-Subki, Ibn al-Jazari and an-Nuwayri.
End quote from Manaahil al-‘Irfaan (1/441)
Secondly:
There is a specious argument that may enter some people’s minds, which says that the isnaads of the recitations mentioned by the imams in their books are well known and limited, but they are ahaad isnaads, so how can it be said that their recitations are mutawaatir?
The response to that is: this is an old specious argument, which was answered by more than one of the scholars of recitation and usool. The leading scholars who specialised in this field, on whose teachings these modes of recitation are based, and to whom the isnaads go back, are not the only ones who were proficient in these modes of recitation or the only ones who specialised in them. Rather these modes of recitation were mutawaatir during their time, and remained so after their time, as there were other scholars like them who also specialised in that field and had other students who learned from them this branch of knowledge, which has to do with the modes of recitation and the rules and regulations governing them.
Imam Sharaf ad-Deen ad-Dimyaati (may Allah have mercy on him) said:
The fact that the isnaads that have to do with the modes of recitation are limited to one group does not mean that the modes of recitation did not have other isnaads. Rather the reports that have to do with the modes of recitation are attributed to them because they are the ones who became specialised in that matter and recorded the names of their shaykhs from whom they learned it, and each of them [the narrators in the isnaads] in his generation had many others who specialised in that field, which would raise the reports to the level of being mutawaatir.
This is the view of the scholars, and the dissenting view of Ibn al-Haajib, who differed with regard to some of what we have mentioned, was refuted by one who was very well versed in this field, namely Ibn al-Jazari, who refuted it at length in his book al-Munjid, which is worth reading.
End quote from Ithaaf Fudala’ al-Bashar fi’l-Qiraa’aat al-Arba‘at ‘Ashar (p. 9)
Ibn an-Najjaar al-Fatoohi (may Allah have mercy on him) said:
Some said that the reports concerning the modes of recitation were aahaad reports, such as at-Tawfi in his Sharh. He said: The fact is that they (the modes of recitation) are widely known as being attributed to them, but they were not widely narrated from them, because the isnaads of the seven imams of recitation for the seven modes of recitation going back to the Prophet (blessings and peace of Allah be upon him) are to be found in the books of recitation, which were transmitted from one scholar to another at a time, so they do not fulfil the conditions of being mutawaatir.
The response to that is as follows: the fact that the isnaads are limited to a particular group does not mean that the modes of recitation were not transmitted via other narrators. The inhabitants of every city used to learn recitation according to the recitation of their Imam, who was one of the Sahaabah or otherwise, so a large number of people would learn from another large number like them, and so on. Therefore the transmission of the recitations was mutawaatir, but the imams who became specialised in the modes of recitation recorded the names of their shaykhs from whom they learned their mode of recitation, and that is why they made their isnaads available (whilst others did not). This is like the reports about the Farewell Pilgrimage which are known to be aahaad, but the reports of the Farewell Pilgrimage continued to be transmitted in the manner of mutawaatir reports, from one large number of people to another, throughout the ages. So one should pay attention to that, and not be deceived by the arguments of those who say that the isnaads of the scholars of recitation are aahaad.
End quote from Sharh al-Kawkab al-Muneer (2/127-128)
Thirdly:
With regard to the questioner’s asking: how can we say that (the modes of recitation) are mutawaatir when the term mutawaatir did not appear before Ibn Mujaahid who was the seventh of seven?
The response to that is as follows:
What is meant by something being mutawaatir is learning something on the basis of certainty when there is no doubt at all, as opposed to learning something on the basis of probability. The level of certainty concerning the soundness of the seven modes of recitation is established, and it was transmitted by way of mutawaatir reports, which effectively gives certainty. And that is the point, regardless of whether this terminology was known at that time or not. This is simply the matter of terminology that has to do with setting out guidelines in various fields of knowledge and developing them. The Arabs (before Islam) used to observe the rules of grammar in their language, giving words case endings according to whether words were nominative, accusative or genitive, and so on, but if the people of the Jaahiliyyah were to come back to life now, none of them would know the terminology of Arabic grammar; in fact none of them knew anything about grammar as people speak of it now.
Similarly, with regard to knowledge of hadith, usool al-fiqh and other branches of Islamic knowledge, the fact that the specific terminology of any particular field appeared later on does not mean that the ideas and concepts that the terminology refers to were not known previously to specialists in that field.
As for the notion that the concept was unknown among people who were not specialists, or that it was not widely used by others in general, that does not undermine the fact that the concept was there, and it does not undermine the soundness of a particular academic issue.
Imam Shams ad-Deen adh-Dhahabi (may Allah have mercy on him) said:
The fact that something is mutawaatir does not necessarily mean that the entire ummah is aware of it. For the scholars of recitation, there are matters that are mutawaatir among them, but not among others. For the fuqaha’ there are issues that are mutawaatir among them and narrated from their imams via mutawaatir reports, of which the scholars of recitation are unaware. Among the hadith scholars, there are mutawaatir hadiths that the fuqaha’ have never heard, or at least for the fuqaha’ they were not mutawaatir; rather they were at the level of probability only. For the grammarians there are definitive issues, and the same is true of the linguists. End quote.
Siyar A‘laam an-Nubala’ (10/171)
See also the answer to question no. 5142
And Allah knows best.