Vijnana Bhairava Tantra
46: If one concentrates on the body as a void, even for a moment, with the mind free from thought, then one attains thoughtlessness and verily becomes that form of void (known as Bhairava).
47: O gazelle-eyed one, (if the aspirant is incapable of sunyabhava immediately), let him contemplate over the constituents of his body like bone, flesh, etc. as pervaded with mere vacuity. (After this practice), his bhavana (contemplation) of vacuity will become steady, (and at last he will experience the light of consciousness).
48: One should contemplate on the skin of the body as a mere wall or partition with nothing inside it. By meditating thus, he reaches a state which transcends all things.
49: O embodiment of good fortune, one who contemplates with closed eyes and one-pointed concentration on the mantra in the middle of the lotus in the heart space achieves the highest spiritual realization.
50: When the body of the yogi is penetrated by consciousness in all parts and his mind which has become firm by one-pointedness is dissolved in the dvadasanta situated in the body, then that yogi whose intellect has become firm experiences the characteristic of Reality.