Mishkat al-Masabih 2220
Zaid b. Thābit said:
Abū Bakr sent for me after the slaughter of those who fought at al-Yamāma and ‘Umar b. al-Khattāb was with him. Abū Bakr told me that ‘Umar had come to him and drawn attention to the extensive slaughter among Qur’ān readers at the battle of al- Yamāma, saying he was afraid that if readers continued to be killed in large numbers at other battles a large amount of the Qur’ān would be lost, and that he therefore thought he should give command that the Qur’ān be collected. He had asked. ‘Umar how he could do a thing which God’s messenger had not done, and ‘Umar, swearing by God that this was best, had kept at him till God made him inclined to do that, and he came to hold ‘Umar’s opinion about the matter. Zaid told how Abū Bakr said to him, “You are an intelligent young man whom we do not suspect and you have been writing down the revelation which came to God’s messenger, so search for the Qur’ān and collect it,” adding: I swear by God that if they had imposed on me the transportation of a mountain it would not have been a heavier load for me than the collecting of the Qur’ān which he ordered me to undertake. I asked how they could do a thing which God’s messenger had not done and Abū Bakr, swearing by God that this was best, kept at me till God made me in­clined to do what He had made Abū Bakr and ‘Umar inclined to do. I therefore searched for the Qur’ān and collected it from leafless palm branches, white stones and the breasts of men till I found the end of sūra at-Tauba (Qur’ān, 9) with Abū Khuzaima al-Ansārī, not having found it with anyone else: "A messenger from among yourselves has come to you . . .” to the end of Barā'a * (Qur’ān, 9 128-129). The sheets were deposited with Abū Bakr till God took him, then with ‘Umar during his lifetime, then with Hafsa, ‘Umar’s daughter. 
* Tauba and Barā’a are alternative titles of sūra 9.

Bukhārī transmitted it.
وَعَنْ زَيْدِ بْنِ ثَابِتٍ قَالَ: أَرْسَلَ إِلَيَّ أَبُو بَكْرٍ رَضِيَ اللَّهُ عَنْهُ مَقْتَلَ أَهْلِ الْيَمَامَةِ. فَإِذَا عُمَرُ بْنُ الْخَطَّابِ عِنْدَهُ. قَالَ أَبُو بَكْرٍ إِنَّ عُمَرَ أَتَانِي فَقَالَ إِنَّ الْقَتْلَ قَدِ اسْتَحَرَّ يَوْمَ الْيَمَامَةِ بِقُرَّاءِ الْقُرْآنِ وَإِنِّي أَخْشَى أَنِ اسْتَحَرَّ الْقَتْلُ بِالْقُرَّاءِ بِالْمَوَاطِنِ فَيَذْهَبُ كَثِيرٌ مِنَ الْقُرْآنِ وَإِنِّي أَرَى أَنْ تَأْمُرَ بِجَمْعِ الْقُرْآنِ قُلْتُ لِعُمَرَ كَيْفَ تَفْعَلُ شَيْئًا لَمْ يَفْعَلْهُ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ؟ فَقَالَ عُمَرُ هَذَا وَاللَّهِ خَيْرٌ فَلم يزل عمر يراجعني فِيهِ حَتَّى شرح الله صَدْرِي لذَلِك وَرَأَيْت الَّذِي رَأَى عُمَرُ قَالَ زَيْدٌ قَالَ أَبُو بَكْرٍ إِنَّكَ رَجُلٌ شَابٌّ عَاقِلٌ لَا نَتَّهِمُكَ وَقَدْ كُنْتَ تَكْتُبُ الْوَحْيَ لِرَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَتَتَبَّعِ الْقُرْآنَ فَاجْمَعْهُ فَوَاللَّهِ لَوْ كَلَّفُونِي نَقْلَ جَبَلٍ مِنَ الْجِبَالِ مَا كَانَ أَثْقَلَ عَلَيَّ مِمَّا أَمَرَنِي بِهِ مِنْ جمع الْقُرْآن قَالَ: قلت كَيفَ تَفْعَلُونَ شَيْئا لم يَفْعَله النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ. قَالَ هُوَ وَاللَّهِ خير فَلم أزل أراجعه حَتَّى شرح الله صَدْرِي للَّذي شرح الله لَهُ صدر أبي بكر وَعمر. فَقُمْت فَتَتَبَّعْتُ الْقُرْآنَ أَجْمَعُهُ مِنَ الْعُسُبِ وَاللِّخَافِ وَصُدُورِ الرِّجَال حَتَّى وجدت من سُورَة التَّوْبَة آيَتَيْنِ مَعَ أَبِي خُزَيْمَةَ الْأَنْصَارِيِّ لَمْ أَجِدْهَا مَعَ أَحَدٍ غَيْرِهِ (لَقَدْ جَاءَكُمْ رَسُولٌ مِنْ أَنْفُسِكُمْ)
حَتَّى خَاتِمَةِ بَرَاءَةَ. فَكَانَتِ الصُّحُفُ عِنْدَ أَبِي بَكْرٍ حَتَّى تَوَفَّاهُ اللَّهُ ثُمَّ عِنْدَ عُمَرَ حَيَاته ثمَّ عِنْد حَفْصَة. رَوَاهُ البُخَارِيّ