Amrita Nada Upanishad, 21st among the 108 Upanishads, forms part of Krishna Yajur Veda. It talks about two different ways of attaining salvation.
For the pure-minded one, having studied the Sastras (Scriptures) he should reflect them over and over again to come to know about the Brahman. Knowing the Brahman, he should abandon them all.
For the impure minded one, the practice of Sadanga Yoga (yoga of six limbs or stages) is prescribed.
The six stages are
- Tarka and
Pratyahara is the subjugation of senses. Senses are of out-going nature towards the objects of senses like sound, taste, etc. The kriya or technique of conquering the senses and bring them to a point is Pratyahara. For Pratyahara, a kriya is explained here. The Yogi should ascend the vehicle of Om, by taking Vishnu as Charioteer or Driver and worshiping Rudra. He should go on like this as long as he can. Then he should abandon the car and proceed further. Then abandoning the stages of syllables and signs, devoid of vowels and consonants, he reaches the subtle Pada or Stage of Brahman by means of the letter ‘m’ devoid of the vowel. This is the kriya for Pratyahara as given in the Upanishad. He should meditate on Brahman by means of the letter ‘m’ devoid of the vowel.
Dhyana means Meditation. The yogi should meditate on Brahman by means of the letter ‘m’ devoid of the vowel.
Pranayama is controlling of Prana. It is of three-fold. Rechaka, Puraka, and Kumbhaka or Rucira. Rechaka is Expiration, Puraka is Inspiration and Kumbhaka is retention. Pranayama is the prolonged breath with reciting Gayatri mantra with Pranava (Om), Vyahrtis and Siras or the Crest of Gayatri.
Dharana means contemplation. Knowing his mind as full of desires, Yogi should merge it with his Atman or own Self and absorbed in the contemplation of Paramatman or Supreme Self is Dharana.
Tarka means inference. Inference should not be against scriptures.
Tarka leads to Samadhi where the Self identifies itself as Supreme Self. In Samadhi, all are equal means Atman and Paramatman are same.