Muhammad is, of course, the major human figure in the religion of Islam. It would therefore be only natural for Muslims to want to find out everything that they can about him. This market is well served by a variety of biographies purporting to fill in every detail of the life of the Islamic prophet. There is just one problem with this whole enterprise. Not even one of the biographies of Muhammad can be viewed as a primary source as all of them date from a much later period.
The most famous and earliest biography of Muhammad of which we have a written record is the Sirat Rasul Allah (Biography of the Apostle of Allah) by Muhammad ibn Ishaq ibn Yasār (often known simply as Ibn Ishaq) who lived from 704-770 CE. It is instructive to focus on his birth and death dates. The author of the earliest biography of Muhammad in written form was born a full 70 years after the date traditionally given for the death of Muhammad and probably started work on his famous biography more than 100 years after Muhammad’s death.
It should, furthermore, be noted that we do not have the actual book, but only references and extended quotes from later biographers like Ibn Hisham (who died in 833 CE, almost exactly 200 years after Muhammad).
It is very significant, when it comes to assessing Ibn Hisham’s passing on of Ibn Ishaq’s writings, that the later author is quite upfront about the fact that he did not simply transmit Ibn Ishaq’s material as he found it. He instead seems to have exercised a significant level of editorial control. Or as he put it: “...confining myself to the prophet's biography and omitting some of the things which Ibn Ishaq has recorded in this book in which there is no mention of the apostle and about which the Quran says nothing and which are not relevant to anything in this book or an explanation of it or evidence for it; poems which he quotes that no authority on poetry whom I have met knows of; things which it is disgraceful to discuss; matters which would distress certain people; and such reports as al-Bakka'i told me he could not accept as trustworthy - all these things I have omitted. But God willing I shall give a full account of everything else so far as it is known and trustworthy tradition is available.”
Hardly the kind of statement designed to inspire ringing confidence that we are dealing with a pristinely preserved historical tradition.
We must conclude, then, that even the most revered of Muhammad’s biographies is hamstrung by the twin impediments of being chronologically far removed from its subject and serious questions about whether its contents was reliably transmitted. This is before we even turn to some of the deeper problems discussed below.