This paper explores the usages of four concepts – sunna, sīra, āthār, and nasab – mainly in early Ibāḍī epistles, but also in other types of Ibāḍī literature, to examine how early Ibāḍīs understood the legacy of the Prophet Muḥammad, and their relation to that legacy. It argues that before the sixth/twelfth century a notion of communal pedigree occupied pride of place in early Ibāḍī conceptualizations of legality and legitimacy. Thus, Ibāḍī sunna was “communal sunna”. The accumulated weight of Ibāḍī tradition – what is known as āthār in Ibāḍī literature – operated authoritatively as a counterpart to sunna; and the Ibāḍī siyar tradition did not focus on the Prophet exclusively, but rather described the scholarly community as an imagined whole. Moreover, Ibāḍīs explicitly articulated their communal pedigree in “teacher lines” (called nasab al-dīn or nasab al-islām) in Omani literature, and through the structure of their ṭabaqāt/siyar works in North Africa. Appreciating the importance of this communal pedigree, and the nexus of concepts through which it was articulated, helps us to understand the relative lack of emphasis placed on collecting and documenting ḥadīth (Ibāḍīs employ ḥadīth, but they did not use isnāds, nor did they appear to have a ḥadīth collection until the sixth/twelfth century), as well as the general absence of Prophetic biography among them (which also does not appear until the sixth/twelfth century).