In circumstances of political and religious conflict, the Islamic ritual sermon could be traumatic, especially when such sermons signaled a change in allegiance from a Sunni to a Shī‘ī ruler (or vice versa). For more than two centuries the Ismaili Fatimids confronted the Abbasids, each claiming for itself the right to be in invoked in the official sermon in the congregational mosques. One dramatic example of this change of loyalty is illustrated by a verbatim copy of what the preacher said on the occasion. This text, together with a few others that have been preserved, offer an opportunity to analysis this genre of preaching in a contested arena.En contextos de conflicto político y religioso, el sermón litúrgico islámico podía ser traumátic...