http://en.wikipedia.org/wiki/Ibn_Ishaq
"He collected oral traditions that formed the basis of the first biography of the Islamic prophet Muhammad. This biography is usually called Sirat Rasul Allah ("Life of God's Messenger")."
"Ibn Isḥaq wrote several works, none of which survive.
His collection of traditions about the life of Muhammad survives mainly in two sources:
an edited copy, or recension, of his work by his student al-Bakka'i, as further edited by Ibn Hisham. Al-Bakka'i's work has perished and only
Ibn Hisham's has survived, in copies.
an edited copy, or recension, prepared by his student Salamah ibn Fadl al-Ansari. This also has perished, and survives only in the copious extracts to be found in the volumimous historian
al-Tabari.
http://en.wikipedia.org/wiki/Ibn_Jarir_al-Tabari
Alfred Guillaume translated the extracts from Ibn Hisham and put them together with those from Tabari to "recreate" this Biography:
http://www.amazon.com/Life-Muhammad-...1502745&sr=1-1