From the 1980s, revisionist Sunni Islamist thinkers have engaged in a hermeneutical effort to argue for the full acceptance of non-Muslims as equal political participants and citizens in an Islamic polity. A key text in their argument is the so-called Constitution of Medina, regulating the interaction between the newly arrived followers of Muhammad and the existing tribes in Medina who were either polytheists or Jews. This paper investigates the sira literature of Muslim Brotherhood in order to gauge the degree to which the life of the Prophet has been reinterpreted to enable such novel readings. It analyzes three popular Muslim Brotherhood siras, by the Syrian Mustafa al-Sibai (1960s), the Egyptian Muhammad al-Ghazzali (1980s), and the Libyan Ali al-Sallabi (2000s). The paper detects important developments in these siras’ treatments of Muhammad’s engagement with non-Muslims—including their interpretations of the Constitution of Medina. These developments, however, do not reflect the radical rethinking of civil society and civility found in the abovementioned revisionist Islamist literature; rather, they evince a more classical Islamist interest in the Prophet as a propagator of Islam as a law and system. That said, this sira literature should be viewed as a genre aiming at the ideological education of brotherhood members, rather than the theoretical exploration of political theory.