Vimalakirti Nirdesa Sutra
Chapter 8: The Buddha Path (13)
Though he knows there is neither birth nor death, he is reborn to show himself to all, appearing in many countries. Like the sun seen by everyone. When making offerings to countless Buddhas in the ten directions, he does not discriminate between himself and them. Although He knows that Buddha lands are void like living beings. He goes on practicing the Pure Land (Dharma) to teach and convert men. In their kinds, features, voices and bearing, this fearless Bodhisattva can appear the same as they. He, knows the mischief demons, do but appears as one of them. Using wise expedient means to look like them at will. Or he appears old, ill and dying to make living beings realize that all things are but illusion, to free them from all handicaps.
The Tibetan Book of the Dead
Book I: The Eighth Day (12.2-12.3)
O nobly-born, the Great Glorious Buddha-Heruka, dark-brown of colour; with three heads, six hands, and four feet firmly postured; the right [face]...
(12) O nobly-born, the Great Glorious Buddha-Heruka, dark-brown of colour; with three heads, six hands, and four feet firmly postured; the right [face] being white, the left, red, the central, dark-brown; the body emitting flames of radiance; the nine eyes widely opened, in terrifying gaze; the eyebrows quivering like lightening; the protruding teeth glistening and set over one another; giving vent to sonorous utterances of 'a-la-la' and 'ha-ha', and piercing whistling sounds; the hair of a reddish-yellow colour, standing on end, and emitting radiance; the heads adorned with dried [human] skulls, and the [symbols of the] sun and moon; black serpents and raw [human] heads forming a garland for the body; the first of the right hands holding a wheel, the middle one, a sword, the last one, a battle-axe; the first of the left hands, a bell, the middle one, a skull-bowl, the last one, a ploughshare; his body embraced by the Mother, Buddha-Krotishaurima, her right hand clinging to his neck and her left putting to his mouth a red shell [filled with blood], [making] a palatal sound like a crackling [and] a clashing sound, and a rumbling sound as loud as thunder; [emanating from the two deities] radiant flames of wisdom, blazing from every hair-pore [of the body] and each containing a flaming dorje; [the two deities together thus], standing with [one] leg bent and [the other] straight and tense, on a dais supported by horned eagles, will come froth from within thine own brain and shine vividly upon thee. Fear that not. Be not awed. Know it to be the embodiment of thine own intellect. As it is thine own tutelary deity, be not terrified. Be not afraid, for in reality is it the Bhagavan Vairochana, the Father-Mother. Simultaneously with the recognition, liberation will be obtained: if they be recognized, merging [thyself], in at-one-ment, into the tutelary deity, Buddhahood in the Sambhoga-Kaya will be won.
Chapter 14 (6)
“Subhuti, five hundred incarnations ago, I recollect that as a recluse practising the ordinances of the Kshanti-Paramita, even then I had no such...
(6) “Subhuti, five hundred incarnations ago, I recollect that as a recluse practising the ordinances of the Kshanti-Paramita, even then I had no such arbitrary ideas as an entity, a being, a living being, or a personality. Therefore, Subhuti, an enlightened disciple ought to discard as being unreal and illusive, every conceivable form of phenomena. In aspiring to supreme spiritual wisdom, the mind ought to be insensible to every sensuous influence, and independent of everything pertaining to sound, odour, taste, touch, or Law. There ought to be cultivated a condition of complete independence of mind; because, if the mind is depending upon any external aid, it is obviously deluded—there is in reality nothing external to depend upon. Therefore, the Lord Buddha declared that in the exercise of charity, the mind of an enlightened disciple ought not to depend upon any form of phenomena. Subhuti, an enlightened disciple desirous to confer benefits upon the whole realm of being, ought thus to be animated in the exercise of charity.”