In order to reach that Brahmarandhra, one has to diligently ascend, Chakra by Chakra to the Bhrumadhya (center of the eyebrows).
- Shri JnanendranathMukhopadyay from the introduction to Pranab Gita
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)
Taking it via the upward moving, sattva-endowed sushumna and going up to the “r[a]” = Eye; “dhi” = after stilling the mind there, “a” [=] again coming [down] to the Muladhar... Bringing it to the Eye + “a” = again taking it to the Muladhar.
- Yogiraj Shri Lahiri Mahasaya from KRISHNA-YAJURVEDIYA-TEJABINDU UPANISHAD (Verse 3), The Scriptural Commentaries of Yogiraj Sri Sri Shyama Charan Lahiri Mahasaya Volume 1, Yoga Niketan Inc
Do “shikligar” (the term for sword cleaning) to your self. To do “shikligar” upon a sword, go from the base of the weapon to the tip [in one stroke] and again come back to the base. Now do the “shikligar” of Kriya via the Self and clean the self.
- Lahiri Mahasaya from Kabir – Spiritual Commentary by Sri Sri Shyama Charan Lahiri Mahasaya (verse 14), Yoga Niketan, Inc
Kabir is saying that Guru is like the washerman and the disciple is like the cloth – meaning: in the way that a washerman cleans clothes, so does Guru clean the cloth-like disciple with soap – meaning: cleaning the self again and again on the stone of meditation, Boundless Light comes forth. -14
[Lahiri Mahasaya's Commentary:]  Kabir, the Atman-Guru in the body is washing [you] like this: once up and once down.
- Lahiri Mahasaya from Kabir – Spiritual Commentary by Sri Sri Shyama Charan Lahiri Mahasaya (verse 15), Yoga Niketan, Inc