The Qur’an has always been central to Islam and to the religious lives of Muslims, and this has provided the impetus, generation after generation, for them to devote care and attention to memorizing, reciting, preserving and transmitting the Qur’an. Wherever you go in the Muslim world, whether among Sunnis, Twelver Shi`ah, Zaydi Shi`ah or any other sect or school, you find the verses in the same order within the surahs. There is no disagreement on the sequence of verses within the surahs.

There are also numerous hadiths indicating that the order of verses within the surahs was fixed by the Prophet (may Allah bless him and grant him peace) himself:

1. Zayd said, “We used be in the presence of the Prophet (may Allah bless him and grant him peace), gathering the Qur’an from pieces of parchment.” [Narrated by al-Hakim with an isnad on the criteria of Bukhari and Musch surlim]
2. As part of a longer hadith, narrated by `Uthman (may Allah be well-pleased with him), in response to a question from Ibn `Abbas, “…when something [of the Qur’an] came down upon [the Prophet], he summoned some of those who would write, and tell them, ‘Put these verses in the surah that mentions such-and-such.'” [Ahmad, Abu Dawud, Tirmidhi, Nasai, Ibn Hibban, al-Hakim]
3. `Uthman ibn Abi’l-`As mentioned that he was once sitting in the presence of the Messenger of Allah (may Allah bless him and grant him peace) when the Prophet (may Allah bless him and grant him peace) said, “Gabriel came to me and commanded me to put this verse [16:90] in this place in this surah.” [Ahmad with a good chain of naration]
4. When Ibn al-Zubayr questioned `Uthman about the chronology of two verses, `Uthman told him, “I don’t change anything from its position.” [Bukhari]
5. When `Umar kept asking about the kalalah (an issue in inheritance law), the Prophet (may Allah bless him and grant him peace) told him, “The summer verse at the end of Surat al-Nisa’ is enough for you.” [Muslim]
6. There are hadiths about the virtues of certain verses, referring to them by their position in the surah:
• the last verses of Surat al-Baqarah [Bukhari and others]
• the first and last ten verses of Surat al-Kahf [Muslim and others]
7. There are hadiths telling us that the Prophet (may Allah bless him and grant him peace) recited certain surahs, from start to finish, often publicly:

• • Hudhayfah ibn al-Yaman heard him reciting al-Baqarah, Aal-`Imran and al-Nisa’ in tahajjud. [Muslim]
  • He recited al-A`raf in Salat al-Maghrib [Bukhari]
  • He recited al-Mu’minun in Fajr, until he reached the part mentioning Prophet Moses (peace be upon him), at which point he was overcome by a cough and went into ruku`. [Nasai]
  • He recited al-Sajdah and al-Insan in Fajr on the day of Jumu`ah [Tabarani]
  • He recited al-Najm in its entirety to the people of Makkah, and did sajdah at the end. [Bukhari]
  • He recited Surat al-Rahman to the jinn. [al-Hakim, Tirmidhi]
  • He recited al-Qamar and Qaf in Salat al-`Id. [Muslim]
  • He recited al-Jumu`ah and al-Munafiqun in Salat al-Jumu`ah. [Muslim]
  • Ibn Sallam said that the Prophet (may Allah bless him and grant him peace) recited al-Saff to them in its entirety when it was revealed. [al-Hakim]

`Allamah al-Suyuti (may Allah bless him) observes that all of this indicates that that the Prophet recited the verses of each surah in a particular order that was fixed. His public and repeated recitations familiarized the Companions with this to the level of tawatur, and they maintained these sequences in the copies of the Qur’an which they compiled. There is also unanimity (ijma`) among the Muslims about this (cited by Zarkashi and others) as mentioned earlier (above).

[The above information is drawn mainly from Jalal al-Din al-Suyuti’s Al-Itqan fi `Ulum al-Qur’an]