Ksurika Upanishad is the 31st among 108 Upanishads and forms part of Krishna Yajur Veda. It is one among the twenty yoga upanishads. The Sanskrit word Ksurika means Knife. This Upanishad prescribes yoga that will cut asunder the bondage between Atman and rebirth.
The mode of yoga taught by this Upanishad is Raja yoga or Astanga Yoga.
Secure a silent place in seclusion. Assume any suitable posture. Withdraw all senses of organs. Restrict your mind from wandering and keep it in your heart. Breathe in and mentally chant ohm of four matras. Hold in the air slightly lifting your chest, hip and neck and breathe out gradually.
A kriya of contemplation on Marma Sthana (vital parts) of the body, is now explained. The idea of yoga-nidra given by contemporary yoga gurus is based on this technique only. Having brought his sense organs under control and making his Mind and Prana firm, the yogi should perform Dharana on toes, two ankles, shanks, Knees, thighs, Muladhara, Swathistana. He should fix Mind, Prana, and Atman in Manipura till mastery.
One part at a time only should be taken for Dharana. For moving to next part, the earlier part should be cut off.
Then on Susumna Nadi of white color surrounded by ten other Nadis of different colors which are very subtle and fine, should be mediated. Then on red lotus Anahata should be taken for Dharana. Having broken that lotus, Vishuddha should be taken for meditation. Likewise Anja and then Sahasrara.
While meditating on each Marma sthana, Inner Eye, Mind, and Prana should be concentrated on that part, which is nothing beyond the Brahman. This knowledge will be reached when one has mastery over the kriya. While moving to next part, the earlier part should be cut-off. One exception is Susumna should not be cut off. By doing this kriya, the yogi will become adept in Astanga Yoga. He, having cut off his bondage with the knife of Om and being sharpened by the practice of pranayama, does not bind it again.