The Inferno: Novel Summary: Canto 28
In the Ninth Bolgia, Dante is horrified to see more blood and wounds than were ever created by the worst slaughter of ancient or recent times. The first of the souls who suffer there is Mahomet (Mohammed), whose whole body is sliced almost in two; he explains that all the souls here in their lives created divisions, and so here they are wounded by a devil. The wounds have closed by the time they get around the circle again, and the devil wounds them again. Two of the souls he speaks to here tells of someone living who will soon be here. One with his hands cut off confesses himself to be the man who urged on the murder that started the feuding of Guelph and Ghibelline in Florence. Finally, most unbelievable horror, the poet who encouraged a young prince to rebel against his father walks carrying his own head like a lantern. He holds his head up to speak to them, confessing his deed and the appropriateness of his suffering.
Mohammed was believed by medieval Christians to have been Christian himself and then to have turned against the Church, leading to all the warfare of the Muslim conquest of North Africa and Spain, and then of the Crusades, just ending in complete defeat for the Christian side in Dante's day. These are the sowers of discord where there should have been harmony and unity; they have used their (often great) gifts of intelligence and persuasion in a way that has disrupted the natural (and therefore divine) order of things and led to endless wounds and blood.