As to the notion of Nirvana as held by disciples and masters who still cling to the notion of an ego-self, and who try to find it by going off by themselves into solitude: their notion of Nirvana is an eternity of bliss like the bliss of the Samadhis-for themselves. They recognize that the world is only a manifestation of mind and that all discriminations are of the mind, and so they forsake social relations and practice various spiritual disciplines and in solitude seek self-realization of Noble Wisdom by self-effort. They follow the stages to the sixth and attain the bliss of the Samadhis, but as they are still clinging to egoism they do not attain the "turning-about" at the deepest seat of consciousness and, therefore, they are not free from the thinking-mind and the accumulation of its habit-energy. Clinging to the bliss of the Samadhis, they pass to their Nirvana, but it is not the Nirvana of the Tathagatas. They are of those who have "entered the stream"; they must return to this world of life and death.

(The Lankavatara Sutra)