The Pali Canon strictly tells us about non-self. Buddha teaches anatta (no-self) doctrine.
However, in some Mahayana sutras such as Tathagatagarbha sutras, Buddha started to teach eternal, imperishable, unchanging self. (Atman)
Professor Michael Zimmermann, a specialist on the Tathāgatagarbha Sutra, writes: "the existence of an eternal, imperishable self, that is, buddhahood, is definitely the basic point of the Tathagatagarbha Sutra"
http://en.wikipedia.org/wiki/%C4%80tman_(Buddhism)
Direct quotes from Mahayana Mahaparinirvana Sutra:
"The Tathagata also teaches, for the sake of all beings, that, truly, there is the Self (Atman) in all phenomena." "You, monks,
should not thus cultivate the notion (samjna) of impermanence, suffering and non-Self, the notion of impurity and so forth, deeming them to be the true meaning [of the Dharma], as those people [searching in a pool for a radiant gem but foolishly grabbing hold of useless pebbles, mistaken for priceless treasure] did, each thinking that bits of brick, stones, grass and gravel were the jewel. You should train yourselves well in efficacious means.
In every situation, constantly meditate upon [bhavana] the idea [samjna] of the Self, the idea of the Eternal, Bliss, and the Pure ... Those who, desirous of attaining Reality [tattva], meditatatively cultivate these ideas, namely, the ideas of the Self [atman], the Eternal, Bliss, and the Pure, will skilfully bring forth the jewel, just like that wise person [who obtained the genuine, priceless gem, rather than worthless detritus misperceived as the real thing.]"
"The Self (ātman) is reality (tattva), the Self is permanent (nitya), the Self is virtue (guṇa), the Self is eternal (śāśvatā), the Self is stable (dhruva), the Self is peace (siva).”
“The True Self is the Tathāgata-dhātu [Buddha-Principle, Buddha Element, Buddha-Factor]. You should know that all beings do have it, but it is not apparent, since those beings are enveloped by immeasurable kleśas [mental and moral afflictions) ….”
I`m confused, does "eternal, imperishable, immortal" Atman exits in Buddhism or not?