1) Some of the Sahabah who memorized the Quran are: • Abu Bakr sadiq • Umar ibn al-Khattaab • Uthman ibn 'Affaan • Ali ibn Abi Taalib • Ubayy ibn Ka'b • Abdullah ibn Mas'ood ibn Ghaafil • Umm Salamah Hind bint Abi Umayyahl • Zayd ibn Thaabit ibn ad-Dahhaak • Abu Moosa al-Ash'ari • Abu'd-Darda' Uwaymir in Zayd al- Ansaari • Abu Hurayrah ad-Dawsi • Abdullah in 'Abbaas ibn 'Abd al- Muttalib • Aa'ishah bint Abi Bakr • Abdullah in as-Sayyib ibn Abi's-Saa'ib • Mu'adh ibn Jabal • Saalim the freed slave of Abu Hudhayfah • Abdullah ibn 'Umar ibn al- Khattaab 2) Some of the scribes, who wrote down the Quran: • Abu Bakr al-Siddeeg • 'Umar in al-Khattaab • 'Uthmaan in 'Affaan • 'Ali ibn Abi Taalib • al-Zubayr ibn al-'Awwaam • 'Aamir ibn Fuhayrah • 'Amr ibn al-'Aas, Ubayy ibn Ka'b • 'Abd-Allaah ibn al-Arqam • Thaabit in Qays ibn Shammaas • 'Abd-Allaah in Rawaahah • Khaalid ibn al-Waleed • Khaalid ibn Sa'eed ibn al-'Aas • Mu'aawiyah ibn Abi Sufyaan • Zayd in Thaabit • Hanzalah in al-Rabee' al- Usaydi • al-Mugheerah ibn Shu'bah 3) Abrogation It is important as Muslims to be aware that we do affirm that verses may have being abrogated (By Allah), as the Quran explicitly states in Surah Al-Baqarah, Verse 106: "Any revelation We cause to be superseded or forgotten, We replace with something better or similar. Do you [Prophet] not know that God has power over everything?". 4) Manucripts We have around-about 250,000 extant Quranic manuscripts ['Muhammad Mustafa Al-Azami, 'The History of the Quranic text, 2nd edition', Chapter 12] We also have about 2-dozen manuscripts from the 1st Islamic century, and 100% of the Quran is attested for within the late 1st/early 2nd Islamic centuries. Another point which is significant and worth mentioning, is that we have manuscripts which are dated back to the prophet Muhammad (SAW)'s time. [https://www.islamic-awareness.org/quran/text/mss/]