" Over the course of those ten days of his illness, all of the men who were to be the first five caliphs of Islam would be in and out of his sickroom: two fathers-in-law, abu-Bakr and Omar; two sons-in-law, Ali and Uthman; and a brother-in-law, Muawiya. But how that would happen, and in what order, was to remain the stuff of discord. "

― Lesley Hazleton , The First Muslim: The Story of Muhammad