I turned my breath inwards, and pierced through the six chakras of the body, and my awareness was centered on the Primal Void of the Absolute Lord
- Sri Guru Granth Sahib Ji - Ang 333
"According to Sadguru's instructions, uniting the moon-like sattvic mind to the totality of rajoguna manifesting in the prana vayu [prana airs] and working this united form within the sushumna, traveling the six lotuses from the
two-petaled[Ajna between the eyebrows] to the Muladhar, the furthest point from the Sun - the jiva-Consciousness revealed in the Sahasrara - and again traveling through the six lotuses from the Muladhar to the two-petaled lotus - the nearest point to the Sun revealed as Consciousness - one month's work [evolution] is accomplished. This means that within this short time all blood and flesh in the body is purified of material coagulation; thus, related addictions are also purified and the body begins to be prepared for the Holy Consciousness-substance. In this way, shooting the prana united with mind to the Muladhar and again drawing it from there is called one "kriya of  pranayam" in yogic scriptures. By this, samskaras are removed from consciousness and happiness is maintained."
- Swami Sri Yukteshvar Giriji from his Gita Commentary, Ch 4
Lahiri Mahasay:
Duraradhyam = duh = being far away from Brahman + a = muladhar + aa = the upward bound Truth/true energy/being (Satwastha) rising via the sushumna after staying in the muladhar for a long time,
ra = eye, up to the [eye],
dhi = stabilizing the buddhi [attention/mind] there,
a = coming again to the muladhar.
Durashrayam = being far away from Brahman, there is no sanctuary/shelter (ashraya) without Brahman, and nothing is possible. Ashraya (sanctuary/shelter) means Kriya.
 A= at the muladhar + sha = jiva +
ra = bringing it to the eye +
 a = again taking it to the muladhar.
Dustaram = d = sound yoni + u = sound muladhar. Meaning – putting a little force at the muladhar + ta = again
putting force at the muladhar + ra = eye.
In meditation, after doing 1,728 pranayam the "muni" (sage) has spontaneously/naturally become "mouni" (silent).
The sage-mind is said to be lord – meaning that the mind itself has become Brahman – meaning the post-kriya
- Lahiri Mahasay from  Krishna-Yajur-Tejabindu Upanishad
To move prana in each of the chakras from Muladhara to Ajna as instructed
by Gurudeva is the karmakanda of sadhana
- Swami Pranabananda Giriji Maharaj from Pranab Gita, Chapter 3, Verse 1 (English translation copyright of Yoga Niketan, Inc)
Pranayama, to move Prana properly in six Chakras is his Sadhana and there is no other Sadhana (for him). This is “Aarurukshu state”. By Pranayam, raising from one Chakra to another and finally to Ajna Chakra,
by withdrawal of Karmas, one also abandons the Prana-karma effortlessly. Then one attains Shama-peace.
- Swami Pranabananda Giriji Maharaj from Pranab Gita, Chapter 6, Verse 3 (English translation copyright of Yoga Niketan, Inc)
Because, during the stage without proper Kriya, the paths in all the nerve channels (naadis) are blocked due to Vayu and Phlegm. Because of it, in the beginning, when pushing the prana upwards with force, it encounters the resistance and due to unclear path in the nerves, the clusters of naadis become dry and exhausted and produce the adverse effect. Hence it is advised that the Prana has to be raised gradually and slowly. First, the prana has to be raised slowly with skill and very naturally. With discipline, in-breath and out-breath has to be moved from Muladhara chakra in gradual steps and prana has to be controlled.
- Swami Pranabananda Giriji Maharaj from Pranab Gita, Chapter 6, Verse 25 (English translation copyright of Yoga Niketan, Inc)