Authority on the Holy Qur'an According to Hazrat Umar (ra)
Once, Hazrat Umar Farooq (ra) was at Arafat when a man approached him and said, “O Leader of the Faithful (this is after he was elected as the Khalifa) I have come from Kufa and I have seen a man there dictating the Holy Quran without looking.” Hazrat Umar (ra) said angrily, “Woe to you! (This is a style of speech of the Arabs) Who is this man?” The man replied fearfully, “Abdullah bin Mas‘ud.” When Hazrat Umar (ra) heard this his temper subsided and returned to the state he was in before. He then said, “In terms of undertaking this task, I do not see anyone more worthy and befitting than Abdullah bin Mas‘ud.”
(Masnad Ahmad bin Hanbal, Vol. 1, p. 128, Hadith no. 175, Alim-ul-Kutb, Beirut, 1998).
He could write the entire Holy Quran without looking.
Hazrat Umar (ra) states, “One night, Hazrat Abu Bakr (ra) and I were in the company of the Holy Prophet (sa) when we passed by Abdullah bin Mas‘ud who was reciting the Holy Quran whilst offering voluntary prayers. He was standing in prayer reciting and the Holy Prophet (sa )stood listening to his recitation. Hazrat Abdullah bin Mas‘ud then bowed and went into prostration. The Holy Prophet (sa) said, ‘O Abdullah, whatever you now ask of God will be granted to you.’ The Holy Prophet (sa) then departed saying, ‘Whoever desires to read the Holy Quran with such freshness as though it was just revealed, then he should learn the Holy Quran from Abdullah bin Mas‘ud.’” This Hadith and narration is of Musnad Ahmad bin Hanbal.
(Masnad Ahmad bin Hanbal, Vol. 1, pp. 156-157, Hadith no. 265, Alim-ul-Kutb, Beirut, 1998)