Yajur Veda · Krishna Yajur Veda (Yoga Upanishad group) · 171 mantras
Yoga Kundalini Upanishad
Yoga-kuṇḍaly-upaniṣad
Central theme: Awakening kundalini through pranayama, mudras and khechari
Three chapters, 171 mantras. The most technical of the kundalini-yoga Upanishads. Chapter 1 details saraswati-chalana (the "stirring of Saraswati" — a manipulation of the sushumna at the navel) and the pranayama-mudra combinations (especially shakti-chalana with the four bhutas) that rouse the coiled serpent-power at the muladhara and drive her up the central channel through the six chakras to the sahasrara. Chapter 2 is a complete manual of khechari-mudra — the lengthening, milking and severance of the frenulum until the tongue reverses into the nasopharynx and drinks the amrita of the lunar plexus, conferring physical immortality. Chapter 3 closes with the description of the three avasthas culminating in videha-mukti and the soundless turiya.
Yoga Kundalini 1.86
कुण्डलिन्याः समुद्भूतां गायत्रीं प्राणसंयुताम् । ज्ञानमुद्रां च मां प्राप्य संसारं तरते नरः
Kuṇḍalinyāḥ samudbhūtāṁ gāyatrīṁ prāṇa-saṁyutām, jñāna-mudrāṁ ca māṁ prāpya saṁsāraṁ tarate naraḥ
Reaching the Gayatri risen from Kundalini, joined with prana, and the jnana-mudra — that I am — a man crosses samsara.
The serpent is not a metaphor — she sleeps until prana drives her up the spine.