In his work "Commanding Right and Forbidding Wrong in Islamic Thought" (Cambridge, 2000), Michael Cook, in the chapter on the doctrine of "al-Amr bi'l-Ma"ʿ"rūf wa'l-Nahy" ʿ"an il-Munkar" among the Ibāḍīs, makes a comparison between western and eastern Ibāḍism and with the doctrines of the other Islamic sects and schools. The eastern and western Ibāḍīs represent two distinct historical communities with largely separate literary heritages, at least until, roughly, the beginning of the twentieth century. There are occasional links between them: one shared literary borrowing (Māwardī, Ghazālī), the unusual doctrine that the verbal obligation does not lapse when the offender will not listen, the equally unusual interest in women as performers of the duty. Differences are likely to reflect the very different political histories of the two wings of the sect. In Oman, the resilience of the Imamate down the centuries finds obvious and direct expression in the frequency with which the Omani sources link forbidding wrong with this institution. In the West, where the vacuum left by the disappearance of the Imamate was filled in part by clerical organisation and authority, the scholars seem to have become less cautious about the role of the individual performer. Comparing the Ibāḍī doctrine of forbidding wrong with the doctrines of other Islamic sects and schools, the significant point is that, left aside the close association of forbidding wrong with righteous rebellion and state-formation which the Ibāḍīs share with the Zaydīs, Ibāḍī views do not in any systematic way diverge from those of the Islamic mainstream.