Ibn Ishaq (recension of Ibn Hisham), Sirat Rasul Allah, translated by A. Guillaume as The Life of Muhammad

This is A. Guillaume's standard English translation of the Sirat Rasul Allah, the earliest surviving full biography of Muhammad, originally compiled in the mid eighth century by Ibn Ishaq and preserved only through the later recension of Ibn Hisham, since Ibn Ishaq's own original text does not survive independently. Its strength as a primary source is unmatched for its subject, it is the foundational biographical tradition on which most later accounts of Muhammad's life draw. Its limit is the two layers built into the text itself: a gap of over a century between the events described and Ibn Ishaq's compilation of them, and a further layer of Ibn Hisham's own editorial selection and omission in producing the surviving recension, so a specific detail's reliability depends on which of those layers it comes from, a distinction the text's own transmission history makes unavoidable.