Musnad Ahmad 3:1

Yahya ibn Sa'id narrated to us, 'Awf narrated to us, Yazid—meaning al-Farisi—narrated to us. My father, Ahmad ibn Hanbal, said: And Muhammad ibn Ja'far narrated to us, 'Awf narrated to us, from Yazid, who said: Ibn 'Abbas said to us: I said to 'Uthman ibn 'Affan: "What compelled you to take the *Anfal* (Surah 8), and it is from the *Mathani* (surahs with fewer than 100 verses), and *Bara'ah* (Surah 9), and it is from the *Mi'in* (surahs with about 100 verses), and join them together, and not write—Ibn Ja'far said: between them—a line: 'In the name of Allah, the Entirely Merciful, the Especially Merciful,' and place them among the *Sab' al-Tiwal* (the seven long surahs)? What compelled you to do that?" 'Uthman said: "Indeed, the Messenger of Allah (peace and blessings of Allah be upon him) would have a time come upon him when surahs of various numbers would be revealed to him. When something was revealed to him, he would call for some of those who used to write for him and say: 'Place this in the surah in which such-and-such is mentioned.' And verses would be revealed to him, and he would say: 'Place these verses in the surah in which such-and-such is mentioned.' And a verse would be revealed to him, and he would say: 'Place this verse in the surah in which such-and-such is mentioned.' *Anfal* was among the first of what was revealed in Medina, and *Bara'ah* was from the last of the Qur'an, and its subject matter was similar to its subject matter. The Messenger of Allah (peace and blessings of Allah be upon him) passed away and did not clarify to us that it was from it (i.e., part of it). I thought that it was from it, and for that reason, I joined them together and did not write between them a line: 'In the name of Allah, the Entirely Merciful, the Especially Merciful.'" Ibn Ja'far said: "And I placed them among the *Sab' al-Tiwal*."