Overview of the Transmission
There are two longer complexes of traditions about the hiǧra, covering the situation of the Muslims in Mecca after the first revelations, the emigration of some Muslims to Abyssinia, and finally the emigration to Medina. One tradition is preserved in the form of a letter from ʿUrwa to the caliph ʿAbd al-Malik, the longest version of which is quoted by al-Ṭabarī according to the transmission of Hišām b. ʿUrwa ← ʿUrwa. However, al- Ṭabarī also claims to have known the letter in the transmission according to Abū l-Zinād ← ʿUrwa. A shorter version of the letter in the Hišām transmission is found in Ibn Ḥanbal's Musnad. In addition, there are shorter (lecture-based) traditions according to Hišām, which mostly correspond quite closely to parts of the letter in terms of content, but which also contain additional material. They only concern events of the actual hiǧra.
A second long tradition, which likewise links the situation of the Muslims in Mecca with the emigration to Abyssinia and the emigration to Medina, is preserved in various traditions according to al-Zuhrī ← ʿUrwa. In this case as well, in addition to the long tradition, there are several shorter traditions that contain individual elements corresponding to the long tradition.
A medium-length tradition transmitted through Muḥammad b. ʿAbd al-Raḥmān ← ʿUrwa deals only with the emigration to Medina, while another tradition according to Muḥammad b. Ǧaʿfar ← ʿUrwa only covers the arrival in Medina.
Finally, there are a number of traditions which are linked to the hiǧra in some way, but which do not concern the history of the hiǧra itself and thus have no parallel in the long traditions.
Longer traditions transmitted through Abū l-Aswad ← ʿUrwa (partly parallel to Mūsā b. ʿUqba ← al-Zuhrī) will not be examined here.
The Transmission According to Hišām b. ʿUrwa
ʿUrwa's Letter to the Caliph ʿAbd al-Malik
The most detailed account of the events surrounding the hiǧra in the transmission according to Hišām b. ʿUrwa is a letter from ʿUrwa to the caliph ʿAbd al-Malik. The longest version of this letter has been handed down by al-Ṭabarī. A shorter version is preserved by Ibn Ḥanbal. Al-Ṭabarī's version is not transmitted in one piece, but is divided into several parts, interrupted by other traditions.