Narrated Zaid bin Thabit Al-Ansari:

who was one of those who used to write the Divine Revelation: Abu Bakr sent for me after the (heavy) casualties among the warriors (of the battle) of Yamama (where a great number of Qurra' were killed). `Umar was present with Abu Bakr who said, `Umar has come to me and said, The people have suffered heavy casualties on the day of (the battle of) Yamama, and I am afraid that there will be more casualties among the Qurra' (those who know the Qur'an by heart) at other battle-fields, whereby a large part of the Qur'an may be lost, unless you collect it. And I am of the opinion that you should collect the Qur'an." Abu Bakr added, "I said to `Umar, 'How can I do something which Allah's Apostle has not done?' `Umar said (to me), 'By Allah, it is (really) a good thing.' So `Umar kept on pressing, trying to persuade me to accept his proposal, till Allah opened my bosom for it and I had the same opinion as `Umar." (Zaid bin Thabit added:) `Umar was sitting with him (Abu Bakr) and was not speaking. me). "You are a wise young man and we do not suspect you (of telling lies or of forgetfulness): and you used to write the Divine Inspiration for Allah's Messenger (ﷺ). Therefore, look for the Qur'an and collect it (in one manuscript). " By Allah, if he (Abu Bakr) had ordered me to shift one of the mountains (from its place) it would not have been harder for me than what he had ordered me concerning the collection of the Qur'an. I said to both of them, "How dare you do a thing which the Prophet has not done?" Abu Bakr said, "By Allah, it is (really) a good thing. So I kept on arguing with him about it till Allah opened my bosom for that which He had opened the bosoms of Abu Bakr and `Umar. So I started locating Qur'anic material and collecting it from parchments, scapula, leaf-stalks of date palms and from the memories of men (who knew it by heart). I found with Khuza`ima two Verses of Surat-at-Tauba which I had not found with anybody else, (and they were):-- "Verily there has come to you an Apostle (Muhammad) from amongst yourselves. It grieves him that you should receive any injury or difficulty He (Muhammad) is ardently anxious over you (to be rightly guided)" (9.128) The manuscript on which the Qur'an was collected, remained with Abu Bakr till Allah took him unto Him, and then with `Umar till Allah took him unto Him, and finally it remained with Hafsa, `Umar's daughter.

حَدَّثَنَا أَبُو الْيَمَانِ، أَخْبَرَنَا شُعَيْبٌ، عَنِ الزُّهْرِيِّ، قَالَ أَخْبَرَنِي ابْنُ السَّبَّاقِ، أَنَّ زَيْدَ بْنَ ثَابِتٍ الأَنْصَارِيَّ ـ رضى الله عنه ـ وَكَانَ مِمَّنْ يَكْتُبُ الْوَحْىَ قَالَ أَرْسَلَ إِلَىَّ أَبُو بَكْرٍ مَقْتَلَ أَهْلِ الْيَمَامَةِ وَعِنْدَهُ عُمَرُ، فَقَالَ أَبُو بَكْرٍ إِنَّ عُمَرَ أَتَانِي فَقَالَ إِنَّ الْقَتْلَ قَدِ اسْتَحَرَّ يَوْمَ الْيَمَامَةِ بِالنَّاسِ، وَإِنِّي أَخْشَى أَنْ يَسْتَحِرَّ الْقَتْلُ بِالْقُرَّاءِ فِي الْمَوَاطِنِ فَيَذْهَبَ كَثِيرٌ مِنَ الْقُرْآنِ، إِلاَّ أَنْ تَجْمَعُوهُ، وَإِنِّي لأَرَى أَنْ تَجْمَعَ الْقُرْآنَ‏.‏ قَالَ أَبُو بَكْرٍ قُلْتُ لِعُمَرَ كَيْفَ أَفْعَلُ شَيْئًا لَمْ يَفْعَلْهُ رَسُولُ اللَّهِ صلى الله عليه وسلم فَقَالَ عُمَرُ هُوَ وَاللَّهِ خَيْرٌ‏.‏ فَلَمْ يَزَلْ عُمَرُ يُرَاجِعُنِي فِيهِ حَتَّى شَرَحَ اللَّهُ لِذَلِكَ صَدْرِي، وَرَأَيْتُ الَّذِي رَأَى عُمَرُ‏.‏ قَالَ زَيْدُ بْنُ ثَابِتٍ وَعُمَرُ عِنْدَهُ جَالِسٌ لاَ يَتَكَلَّمُ‏.‏ فَقَالَ أَبُو بَكْرٍ إِنَّكَ رَجُلٌ شَابٌّ عَاقِلٌ وَلاَ نَتَّهِمُكَ، كُنْتَ تَكْتُبُ الْوَحْىَ لِرَسُولِ اللَّهِ صلى الله عليه وسلم فَتَتَبَّعِ الْقُرْآنَ فَاجْمَعْهُ‏.‏ فَوَاللَّهِ لَوْ كَلَّفَنِي نَقْلَ جَبَلٍ مِنَ الْجِبَالِ مَا كَانَ أَثْقَلَ عَلَىَّ مِمَّا أَمَرَنِي بِهِ مِنْ جَمْعِ الْقُرْآنِ قُلْتُ كَيْفَ تَفْعَلاَنِ شَيْئًا لَمْ يَفْعَلْهُ النَّبِيُّ صلى الله عليه وسلم فَقَالَ أَبُو بَكْرٍ هُوَ وَاللَّهِ خَيْرٌ، فَلَمْ أَزَلْ أُرَاجِعُهُ حَتَّى شَرَحَ اللَّهُ صَدْرِي لِلَّذِي شَرَحَ اللَّهُ لَهُ صَدْرَ أَبِي بَكْرٍ وَعُمَرَ، فَقُمْتُ فَتَتَبَّعْتُ الْقُرْآنَ أَجْمَعُهُ مِنَ الرِّقَاعِ وَالأَكْتَافِ وَالْعُسُبِ وَصُدُورِ الرِّجَالِ، حَتَّى وَجَدْتُ مِنْ سُورَةِ التَّوْبَةِ آيَتَيْنِ مَعَ خُزَيْمَةَ الأَنْصَارِيِّ، لَمْ أَجِدْهُمَا مَعَ أَحَدٍ غَيْرِهِ ‏{‏لَقَدْ جَاءَكُمْ رَسُولٌ مِنْ أَنْفُسِكُمْ عَزِيزٌ عَلَيْهِ مَا عَنِتُّمْ حَرِيصٌ عَلَيْكُمْ‏}‏ إِلَى آخِرِهِمَا، وَكَانَتِ الصُّحُفُ الَّتِي جُمِعَ فِيهَا الْقُرْآنُ عِنْدَ أَبِي بَكْرٍ حَتَّى تَوَفَّاهُ اللَّهُ، ثُمَّ عِنْدَ عُمَرَ حَتَّى تَوَفَّاهُ اللَّهُ، ثُمَّ عِنْدَ حَفْصَةَ بِنْتِ عُمَرَ‏.‏ تَابَعَهُ عُثْمَانُ بْنُ عُمَرَ وَاللَّيْثُ عَنْ يُونُسَ عَنِ ابْنِ شِهَابٍ‏.‏ وَقَالَ اللَّيْثُ حَدَّثَنِي عَبْدُ الرَّحْمَنِ بْنُ خَالِدٍ عَنِ ابْنِ شِهَابٍ وَقَالَ مَعَ أَبِي خُزَيْمَةَ الأَنْصَارِيِّ‏.‏ وَقَالَ مُوسَى عَنْ إِبْرَاهِيمَ حَدَّثَنَا ابْنُ شِهَابٍ مَعَ أَبِي خُزَيْمَةَ‏.‏ وَتَابَعَهُ يَعْقُوبُ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ‏.‏ وَقَالَ أَبُو ثَابِتٍ حَدَّثَنَا إِبْرَاهِيمُ وَقَالَ مَعَ خُزَيْمَةَ، أَوْ أَبِي خُزَيْمَةَ‏.‏
USC-MSA web (English) reference : Vol. 6, Book 60, Hadith 201
Arabic reference : Book 65, Hadith 4679