By the time Umar became the caliph, Muslims already had the Qur’an in its complete and present-day form. Many verses of the Qur’an also attest to its preserved status before the life of the Prophet ended. The Prophet handpicked the scribes who would copy word for word each ayah (considered as a letter or a word in the Qur’an) under his direct supervision. The known scribes were: Ali b. Abi Talib, Abdullah b. Masud, Abu Dardah, Zayd b. Thabit, Ma’adh b. Jabal, and Salim Mawla Abi Hudayfah. During the lifetime of the Prophet, many of the companions – forty-one of whom are recorded by Ibn Nadeem – had written the entire Qur’an with their own hands; therefore, each copy was known as “the copy of Abdullah b. Masud,” “the copy of Ibn Abbas,” and so on.
In later times, some attempted to credit Abu Bakr and Umar for first compiling the Qur’an, but those who did so neglected the earlier historical references. In reality, Umar not only lacked interest in the Qur’an, but he also cast serious doubt on its completeness and authenticity. Oftentimes, he would inform the people from the minbar (pulpit) that some verses of the Qur’an were removed.
Even more, Umar believed that certain verses were lost with the death of the Prophet. In accordance with al-Bukhari, Umar is related to have said, “Allah sent Muhammad with the truth, and He sent a book to him, and we used to read verses in that book, and we don’t find them anymore.” The “missing” verse that Umar is referring to – in which only he thought – was about stoning of an adulterer.
At times, during the dawn prayers, Umar would recite verses that no one else heard; he called them “al-hafd wal-khul.” As for the entirety of the Qur’an, Umar mentioned that it was composed of a whopping 1,027,000 letters, while the Qur’an consists of just over 300,000 letters.
Umar would argue, for instance, with one of the original transcribers of the Qur’an, Hudayfah. Umar asked him how many verses were in Surah al-Ahzab, and Hudayfah answered that there were 72 or 73. Umar countered that the number of verses in that surah was similar to the number of verses in Surah al-Baqarah, which has 286 verses, implying that over 200 verses of the original surah had been lost. He also said that Surah al-Tawbah (Repentance) was only one-fourth of the original, and that it was first called “Surah al-Adhab (The Punishment)” before the people changed its name to Surah al-Tawbah.
Tafseer, the interpretation of the verses of the Holy Qur’an was also not one of Umar’s strong points. He would often discourage, even react violently when people asked him questions about the meaning of the Qur’an, which he could not answer. When a man came to Umar and inquired about what c. 4:128 meant, Umar hit him rather than admitting that he did not know the answer. Similarly, when someone asked Umar what “fodder” meant in the verse, “We split the earth in fragments and produce therein grain…and fruits and fodder” Umar reproached him saying, “You have the book of your Lord with you. Practice what you know from it, and leave what you do not know.” According to Ibn Abil Hadid, Umar was not concerned with the interpretation (tafseer) of the Qur’an and used to say, “Just recite the Qur’an and do not interpret it (tufassiruhu),” since he himself did not know much about it.
Occasionally, Umar would hear verses of the Qur’an but not recognize them as such. One day, Umar angrily interrupted a man who was reading verse 11 from Surah al-Tawbah because he did not recognize the verse and assumed that the man was inventing it. Defending himself, the man asserted, “Yes, I heard it from Ubay b. Ka’ab,” one of the transcribers of the Qur’an. Then, Umar went to Ubay b. Ka’ab and asked him three times about the verse. Each time he replied, “Yes, I received it from Prophet Muhammad.” After that, Umar left raising his hands and shouting “Allahu akbar (God is Great),” “Allahu akbar,” confessing that the verse was authentic but that he had never heard it before.
Elsewhere, when Umar saw verse nine of Surah al-Jumuah (c. 62) written on a tablet he questioned, “Who dictated this verse to you?” Someone replied that Ubay b. Ka’ab had narrated the verse. Umar said, “The Prophet has died and we did not read this verse the way it is written here.” He then continued that the verse should have read “fa umdhu ilaa dhikr Allah,” instead of “fasaw ilaa dhikr Allah” (with both versions having the same meaning of “march” or “go”).
Umar himself knew that his knowledge of the Qur’an was lacking because once when he heard a man read verse 107 of Surah al-Maidah, he told him, “You are a liar.” The man rebuked, “You are a liar.” Another man interjected, “Are you denying that the Commander of the Faithful is saying the truth?” The man replied, “No, I respect the Commander of the Faithful, but he is unaware of the Qur’an.” Umar admitted, “He is telling the truth (sadaq).”
One of the scribers of the Qur’an, Ubay b. Ka’ab commented, “I was busy with the Qur’an during the time of the Prophet, but you (Umar) were busy walking in the markets and in the streets.”
An assailant stabbed Umar b. al-Khattab on Wednesday, four days before the end of Dhul Hijjah in 23 AH. As his condition worsened he realized that his life was about to end, thus he began addressing the subject of his impending death with apprehension and anxiety. Abdullah b. Amar b. Rabiah relates:
I saw Umar when he was on his deathbed, holding in his hand a piece of straw. He raised it and said, “I wish I was this straw. I wish I was nothing. I wish my mother had not delivered me.” 
Soon after, he said:
I wish I was a male sheep in my family. They would feed me and fatten me, and once I became fat, someone who likes my family would visit, so they would slaughter me. They would grill part of me and dry the second half. After that, they would eat me and turn me into adharah (human waste – feces). I wish I was not a human being. 
He expressed a similar sentiment again:
I wish I was a tree on the side of a road, and a camel would pass by and eat me, and start to chew me and swallow me, and then get rid of me as its droppings. I wish I was not a human being. 
These statements raise many questions. Perhaps Umar was regretting how he had treated the Prophet, or how he had accused the Prophet of hallucinating, or how he had delayed the burial of the Prophet until Abu Bakr had returned to participate in the power-sharing talks. Perhaps he regretted tugging on the clothes of the Prophet while he was reading Salat al-Janazah (Prayer of the Deceased); or raising his voice above the voice of the Prophet despite the command of the Qur’an to the contrary (c. 49:2). Maybe at the time of his death, the incident of the attack on the house of Fatima al-Zahra came to his mind.
Just before he died, Umar was resting his head in the lap of his son Abdullah. He asked his son to put his cheek on the ground. His son did not listen, so Umar repeated his words harshly. As soon as his cheek touched the earth, Umar said, “Woe to Umar and to the mother of Umar, if Allah does not forgive Umar.” After the fatal attack on him on Wednesday, Umar was buried the following Sunday, the first day of Muharram, in 24 AH. His khalifah lasted for ten years, five months, and twenty-one days.
 Holy Qur’an, 80:13-15, 76:77-79, 25:5, & 98:2
 Ibn Nadeem, Al-Fihrist, p. 41
 Al-Suyuti, Al-Durr al-Manthur, 5:179
 Sahih al-Bukhari, 10:43; Abu Ubaydah, Al-Itqan, 2:42; Al-Suyuti, Al-Dur al-Manthur, 1:106
 Al-Suyuti, Al-Dur al-Manthur, 3:296; Al-Mutaqi al-Hindi, Kanz al-Ummal, 8:74-75 & 78
 Al-Suyuti, Al-Dur al-Manthur, 6:222; Al-Haythami, Majma al-Zawaid, 7:163; Kanz al-Umal, 1:517
 Musnad Ahmad, 5:132; Mustadrak al-Hakim, 2:415; Sunan al-Bayhaqi, 8:211
 Mustadrak al-Hakim, 2:330; Al-Suyuti, Al-Durr al-Manthur, 1:105
 Al-Muttaqi al-Hindi, Kanz al-Ummal, 1:229; Al-Suyuti, Al-Durr al-Manthur, 6:321
 Holy Qur’an, 80:31
 Al-Suyuti, Al-Durr al-Manthur, 6:317; Al-Muttaqi al-Hindi, Kanz al-Ummal, 2:328
 Ibn Abil Hadid, 3:2 &120
 Al-Muttaqi al-Hindi, Kanz al-Ummal, 2:568
 Al-Muttaqi al-Hindi, Kanz al-Ummal, 2:605
 Sahih al-Bukhari, 3:201
 Ibn Shabbah, Tarikh al-Madinah al-Munawwarah, 2:709
 Al-Muttaqi al-Hindi, Kanz al-Ummal
 Ibn al-Atheer, Usd al-Ghabah
 Al-Suyuti, Tarikh al-Khulafa, 129
 Al-Suyuti, Tarikh al-Khulafa, 142; Muntakhab Kanz al-Ummal, 4:361, 6:365
 Muntakhab Kanz al-Ummal, 4:361
 Sahih al-Bukhari, 1.120; Kitab al-Ilm; Sahih al-Muslim, 11:89
 Tarikh al-Tabari, 2:442; Sirat b. Hisham, 4:305
 Sahih al-Bukhari; Kitab al-Libas; Kanz al-Umaal, hadith 4403