Devibhagavatapurana 7.35.21

7.35.21

uttamasya guṇāvāptiryāvacchīlanamiṣyate |
indriyāṇāṃ vicaratāṃ viṣayeṣu nirargalam ||

Now comes Pratyâhâra. The senses travel spontaneously towards their objects, as if they are without anyone to check. To curb them perforce and to make them turn backwards from those objects is called "Pratyâhâra," To hold the Prâna Vâyu on toes, heels, knees, thighs, sacrum genital organs, navel, heart, neck, throat, the soft palate, nose, between the eyebrows, and on the top of the head, at these twelve places respectively is called the "Dhâranâ." Concentrate the mind on the consciousness inside and then meditate the Ista Devatâ within the Jîvâtmâ. This is the Dhyâna. Samâdhi is identifying always the Jîvâtmâ and Paramâtmâ. Thus the sages say. (Samâdhi is of two kinds (1) Samprajñâta, or Savikalpak and (2) Nirvikalpak. When the ideas the Knower, Knowledge and the Thing Known, rernain separate in the consciousness and yet the mind feels the one Akhanda Sachchidânanda Brahma and his heart remains, there, that is called Samprajñâta Samâdhi; and when those three vanish away and the one Brahma remains, it is called Asamprajñâta Samâdhi). Thus I have described to you the Yoga with its eight limbs. O Mountain! This body composed of the five elements, and with Jîva endowed with the essence of the Sun, the Moon, and the Fire and Brahma in it as one and the same, is denominated by the term "Vis'va." There are the 350,000 nâdis in this body of man; of these, the principal are ten. Out of the ten again, the three are most prominent. The foremost and first of these three is Susumnâ, of the nature of the Moon, Sun, and Fire, situated in the centre of the spinal cord (it extends from the sacral plexus below to the Brahmaradhra in the head at the top where it looks like a blown Dhustûra flower). On the left of this Susumnâ is the Idâ Nâdî, white and looking like Moon; this Nâdî is of the nature of Force, nectar-like. On the right side of the Susumnâ is the Pingalâ Nâdî of the nature of a male; it represents the Sun. The Susumnâ comprises the nature of the all the Tejas (fires) and it represents Fire.