Mahaparinirvana quote about the Buddha-Nature

Chapter Twelve: On the Nature of the Tathagata
"Kasyapa said to the Buddha: "O World-Honoured One! Is there Self in the 25 existences or
not?" The Buddha said: "O good man! "Self" means "Tathagatagarbha" [Buddha-Womb,
Buddha-Embryo, Buddha-Nature]. Every being has Buddha-Nature. This is the Self. Such Self
has, from the very beginning, been under cover of innumerable defilements. That is why man
cannot see it. O good man! [Imagine that] there is a poor woman here. She has true gold
concealed in her house. But none of the people of her house, whether big or small, know of it.
But there is a stranger, who, through expediency, says to the poor woman: "I shall employ you.
You must now go and weed the land!" The woman answers: "I cannot do this now. If you let my
son see where the gold is hidden, I will soon work for you." The man says: "I know the way. I
shall point it out to your son." The woman further says: "Nobody of my house, whether big or
small, knows [of this]. How can you?" The man says: "I shall now make it clear." The woman
says further: "I desire to see. Pray let me." The man digs out the gold that had lain hidden. The
woman sees it, is gladdened, and begins to respect that person. O good man! The case is the
same with the Buddha-Nature which man has. Nobody can see it. This is analogous to the gold
which the poor woman possessed and yet could not see. O good man! I now let persons see the
Buddha-Nature that they possess, which is overspread by defilements. This is analogous to the
poor woman who cannot see the gold, even though she possesses it. The Tathagata now reveals
to all beings the storehouse of Enlightenment, which is the Buddha-Nature, as it is called. If all
beings see this, they are gladdened and will take refuge in the Tathagata. The good expedient is
the Tathagata, and the poor woman is all the innumerable beings, and the cask of true gold is the
Buddha-Nature.