Osiris held one of the most widespread and long-lived cults in ancient Egyptian religion, attested from the Old Kingdom through the Roman period, with Abydos as his principal center and important secondary cult sites at Busiris in the Delta, traditionally linked to his backbone relic, and at Philae, where he was worshipped alongside Isis. Beyond his role as king of the underworld, Osiris presided as judge over the fate of the dead in a ceremony the Book of the Dead calls the weighing of the heart, in which the deceased's heart was placed on a scale against the feather of Ma'at, goddess of truth and order, with Osiris seated in judgment and the monstrous Ammit waiting to devour any heart found too heavy with wrongdoing to pass. A heart that balanced against the feather earned the deceased entry into a blessed afterlife in the Field of Reeds, an Osiris-ruled paradise imagined as a more perfect version of the Nile valley itself. This funerary and judicial role made Osiris central not only to temple cult but to private religious practice at every social level, since virtually every Egyptian funeral invoked him directly, and pharaohs themselves were identified with Osiris upon death, their living son and successor taking the role of Horus in turn. Few Egyptian deities combined major state temple cult and universal personal devotion as completely as Osiris did across more than two thousand years of continuous Egyptian religious practice.