Memorisation

S 2:106 What we abrogate from a verse or cause it to be forgotten we bring better than it or the like of it. Have you not known that Allah is mighty over everything?

Muslims will tell us that quran has been memorised by millions, just not by them themselves. If quran has been memorised, which version? Hafs? Warsh? Al-Duri? Have they memorised the verses of stoning and of adult suckling?

Suckling of Adults

How about the full text of Al-Ahzab?

Wahb ibn Baqiyyah told me: Khaalid ibn ‘Abdullah at-Tahhaan informed me, from Yazeed ibn Abi Ziyaad, from Zirr ibn Hubaysh, from Ubayy ibn Ka‘b, who said: How many (verses) do you recite in Soorat al-Ahzaab? He said: Seventy-odd verses. He said: We recited it with the Messenger of Allah (blessings and peace of Allah be upon him) like al-Baqarah, or more than that, and verily the verse of stoning was in it.

Yazeed ibn Abi Ziyaad is da‘eef (weak), but there is nothing wrong with the hadeeth,as there is corroborating evidence for it.

This indicates that Soorat al-Ahzaab was a lengthy soorah like Soorat al-Baqarah, but most of it was abrogated. Soorat al-Ahzaab was as long as Soorat al-Baqarah, then most of it was abrogated - Islam Question & Answer

If Surat al-Ahzab was of a similar length to Sural al-Baqarah, which is presently 286 verses in length, then why weren't all the verses memorised?

Narrated Kharija bin Zaid:

Zaid bin Thabit said, "When the Qur'an was compiled from various written manuscripts, one of the Verses of Surat Al-Ahzab was missing which I used to hear Allah's Messenger (ﷺ) reciting. I could not find it except with Khuza`ima bin Thabjt Al-Ansari, whose witness Allah's Messenger (ﷺ) regarded as equal to the witness of two men. And the Verse was:-- "Among the believers are men who have been true to what they covenanted with Allah." (33.23)

https://sunnah.com/bukhari:2807

Has the following line, if quranic, been memorised?

Narrated Sahl bin Sa`d:

I heard Ibn Az-Zubair who was on the pulpit at Mecca, delivering a sermon, saying, "O men! The Prophet used to say, "If the son of Adam were given a valley full of gold, he would love to have a second one; and if he were given the second one, he would love to have a third, for nothing fills the belly of Adam's son except dust. And Allah forgives he who repents to Him." Ubai said, "We considered this as a saying from the Qur'an till the Sura (beginning with) 'The mutual rivalry for piling up of worldly things diverts you..' (102.1) was revealed."

https://sunnah.com/bukhari:6438

But if this is Ubay ibn Ka'b, one of those Muslims were/are to take quran from (Hadith - Chapters on Virtues - Jami` at-Tirmidhi - ), he, and others, considered it part of quran, but did still others? How might one judge whether a line is quran or not?

From an article:

According to one report by the son of the second caliph Umar ibn al-Khattab, the present text of the Quran is incomplete since much of it has disappeared:

`Abdullah b. `Umar reportedly said, 'Let none of you say, "I have got the whole of the Qur'an." How does he know what all of it is? MUCH OF THE QUR'AN HAS GONE. Let him say instead, "I have got what has survived."' (Jalal al Din `Abdul Rahman b. Abi Bakr al Suyuti, al-Itqan fi `ulum al-Qur'an, Halabi, Cairo, 1935/1354, Volume 2, p. 25)

We find this same narration cited in Abu Ubaid’s Kitab Fadail-al-Qur’an:

Said Abu ‘Ubaid:

Isma’il b. Ibrahim related to us from Ayyub from Nafi‘ from Ibn ‘Umar who said – Let none of you say, “I have learned the whole of the Koran,” for how does he know what the whole of it is, WHEN MUCH OF IT HAS DISAPPEARED? Let him rather say, “I have learned what is extant thereof.” (Ibn Warraq, Origins of the Koran – Classic Essays on Islam’s Holy Book [Prometheus Books, Amherst, NY 1998], Part Two: The Collections and the Variants of the Koran, 9. Abu ‘Ubaid on the Verses Missing from the Koran, by Arthur Jeffery, p. 151: bold, capital and underline emphasis ours)

The Shia apologists over at the Answering Ansar website have provided another source for this narrative along with its chain of transmitters, demonstrating that this is a reliable report:

One of the early Sunni scholars Qasim bin Salam (d. 222 H) records:

حدثنا إسماعيل بن إبراهيم ، عن أيوب ، عن نافع ، عن ابن عمر ، قال : « لا يقولن أحدكم قد أخذت القرآن كله وما يدريه ما كله ؟ قد ذهب منه قرآن كثير ، ولكن ليقل : قد أخذت منه ما ظهر منه

Ismail bin Ibrahim narrated from Ayub from Naf’ee from Ibn Umar who said: ‘Verily among you people one would say that he has found the Quran whilst he is unaware of what the total quantity of the Quran was, because most of the Quran has been lost. Rather one should say that verily he has found the Quran that has appeared.’ Ismail bin Ibrahim: Dahabi said: ‘Hujja’ (Al-Kashif, vol. 1, p. 242), Ibn Hajar said: ‘Thiqah’ (Taqrib al-Tahdib, vol. 1 p. 90). Ayub al-Sekhtiani: Dahabi said: ‘The master of scholars’ (Siar alam alnubala, vol. 6, p. 15), Ibn Hajar said: ‘Thiqah Thabt Hujja’ (Taqrib al-Tahdib, vol. 1, p. 116). Naf’ee: Dahabi said: ‘The Imam of Tabayeen’ (Al-Kashif, vol. 2, p. 315), Ibn Hajar said: ‘Thiqah Thabt’ (Taqrib al-Tahdib, vol. 2, p. 239). (Fadhail al-Quran by Qasim bin Salam, Volume 2 p. 135) (Who believes the Quran has been a victim of Tahreef?, Chapter Eight: Sunni reports about deletions from the Quran; underline emphasis ours) The Irreparable Loss of Much of the Quran

From another article:

6. Loss of the major part of the Qur'an: There are a lot of traditions in Sunni books which show that the Qur'an was much much more than what the Muslims have in their hands. "At-Tabarani has narrated with trustworthy chain of narrators from 'Umar ibn al-Khattab that he said, 'The Qur'an is one million and twenty seven thousand letters..."12 But the total of the letters in the whole Qur'an is not more than 267,053 as is recorded at the end of many editions of the Qur'an. In other words, three-fourth of the Qur'an was lost!

And the companion 'Abdullah ibn 'Umar is reported as saying, "None of you should ever say, 'I have got the whole Qur'an.' And what would make you know what the whole Qur'an was. Certainly a lot of Qur'an has gone. One should rather say, 'I have got what has appeared from it." 13

Unfortunately the 'ahadith' of major or minor deletions are attributed to many famous personalities of Islam, like Ummu 'l-mu'minin 'A'ishah, Ummu 'l-mu'minin Hafsah, Ummu 'l-mu'minin Umm Salimah, 'Umar ibn al-Khattab, 'Abdullah ibn 'Abbas, 'Abdullah ibn Mas'ud, Abdu'r-Rahman ibn 'Awf, 'Abdullah ibn 'Umar, Zayd ibn Arqam, Jabir ibn 'Abdullah, Buraydah, Maslamah ibn Makhlad, Abu Waqid al-Laythi, and the aunt of Abu Amamah ibn Sahl, in addition to the tabi'in (disciples of the companions) 'Ikrimah and Imam Malik ibn Anas.

These traditions are found in all well-known Sunni books of traditions, including as-Sihahas-Sittah (the six correct books of traditions): Sahih al-Bukhari, Sahih Muslim, Sunan Abi Dawud, Sahih at-Tirmidhi, Sunan an-Nasa'i, Sunan al-Bayhaqi, Musnad of Imam Ahmad ibn Hanbal, Muwatta' of Imam Malik, Ta'rikh of al-Bukhari, Fathu 'l-Ba'ri (Sharh Sahih al-Bukhari) of Ibn Hajar al-'Asqalani, Kanzu 'l-'Ummal of Mulla 'Ali al-Muttaqi, Tafsir ad-Durru'l-Manthur and al-Itqan of As-Suyuti, Jami'u 'l-Usul, al-Muhadarat of Imam ar-Raghib al-Isfihani, Jami 'u 'l-Jawami, Hilyatu 'l-awliya' of Hafiz Abu Nu'aym and al-Mustadrak 'alas-Sahihayn of Imam al-Hakim an-Nishapuri.1 Some Ahadith of Omission | The Quran: Its Protection from Alteration | Al-Islam.org

If memory is so reliable, if Muslims memorised and have memorised quran, why was it written down? Why did Uthman commission a standard version of quran?

Quran in Arabic, for translations are but 'interpretations of the meaning' of quran and not quran itself, is memorised by a small number of Muslims but were quran of value, what might be the value of memorising what you don't understand? How might that benefit the memoriser, or anyone else?