It is narrated from Sayyiduna Umar (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Whoever would like to recite the Qur'an fresh just as it was revealed, let him recite it according to the recitation of Ibn Umm Abd (Abdullah bin Mas'ud)." This narration of Alqamah from Sayyiduna Umar (may Allah be pleased with him) is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it. My supposition is that, in their view, Alqamah bin Qays's hearing from Sayyiduna Umar is not established; and Allah knows best. And it has a detailed supporting narration (shahid) narrated from Sayyiduna Ammar bin Yasir (may Allah be pleased with him) as well.

It is narrated from Sayyiduna Ammar bin Yasir (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) passed by Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) while he was reciting (the Qur'an) letter by letter, and he (peace and blessings be upon him) said: "Whomever it pleases to recite the Qur'an just as it was revealed, let him recite it according to the recitation of Ibn Mas'ud."

It is narrated from Abu Maysarah Amr bin Shurahbil (may Allah have mercy on him) that he said: A man came to me while I was praying and said: May your mother lose you! Do I not see you praying, when it has been ordered concerning the Book of Allah that it be torn to pieces? He says: So I shortened my prayer, and I did not stop anywhere (after the prayer). I entered the house and went straight up, and there I saw Abu Musa al-Ash'ari, Hudhayfah and Ibn Mas'ud (may Allah be pleased with them) arguing with one another. Hudhayfah (may Allah be pleased with him) was saying to Ibn Mas'ud: Hand this mushaf of yours over to them. Ibn Mas'ud said: By Allah! I will never hand it over. The Messenger of Allah (peace and blessings be upon him) taught me more than seventy surahs, and then I should hand it over to them? By Allah! I will not hand it over to them. This hadith has an authentic chain (sahih al-isnad), but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that he said: I recited seventy surahs directly from the blessed mouth of the Messenger of Allah (peace and blessings be upon him), while (in those days) Zayd bin Thabit was a boy with two locks of hair (braids) who used to play with the children. This hadith has an authentic chain (sahih al-isnad), but the two Shaykhs (Bukhari and Muslim) did not record it.

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that he said: The Messenger of Allah (peace and blessings be upon him) taught me seventy surahs, which I had mastered even before Zayd bin Thabit accepted Islam.