A great number of Pyramid Texts present the different phases of the ritual assimilation of the dead pharaoh with Osiris.
As he (Osiris) lives, this king Unis lives; as he dies not, this king Unis dies not; as he perishes not, this king Unis perishes not (Pyr. Ut. 219).
[The dead pharaoh receives the throne of Osiris, and becomes, like him, king of the dead.]
Ho! king Neferkere (Pepi II)! How beautiful is this! How beautiful is this, which thy father Osiris has done for thee ! He has given thee his throne, thou rulest those of the hidden places (the dead), thou leadest their august ones, all the glorious ones follow thee (Pyr. 2022-3).