Bismillah is the First Ayah of Al-Fatihah
The Companions started the Book of Allah with Bismillah:
[بِسْمِ اللَّهِ
الرَّحْمَـنِ الرَّحِيمِ ]
(1. In the Name of Allah, the Most Gracious, the Most Merciful.)
The scholars also agree that Bismillah is a part of an Ayah in Surat An-Naml
(chapter 27). They disagree over whether it is a separate Ayah before every
Surah, or if it is an Ayah, or a part of an Ayah, included in every Surah where
the Bismillah appears in its beginning. Ad-Daraqutni also recorded a Hadith from
Abu Hurayrah from the Prophet that supports this Hadith by Ibn Khuzaymah. Also,
similar statements were attributed to `Ali, Ibn `Abbas and others.
The opinion that Bismillah is an Ayah of every Surah, except Al-Bara'ah
(chapter 9), was attributed to (the Companions) Ibn `Abbas, Ibn `Umar, Ibn
Az-Zubayr, Abu Hurayrah and `Ali. This opinion was also attributed to the
Tabi`in: `Ata', Tawus, Sa`id bin Jubayr, Makhul and Az-Zuhri. This is also the
view of `Abdullah bin Al-Mubarak, Ash-Shafi`i, Ahmad bin Hanbal, (in one report
from him) Ishaq bin Rahwayh and Abu `Ubayd Al-Qasim bin Salam. On the other
hand, Malik, Abu Hanifah and their followers said that Bismillah is not an Ayah
in Al-Fatihah or any other Surah. Dawud said that it is a separate Ayah in the
beginning of every Surah, not part of the Surah itself, and this opinion was
also attributed to Ahmad bin Hanbal.