Patanjali Yoga Sutra 3.40

Sanskrit Sutra

उदानजयाज्जलपङ्ककण्टकादिष्वसङ्ग उत्क्रान्तिश्च॥४०॥

Swami Vivekananda's translation

By conquering the current called Udāna the Yogi does not sink in water or in swamps, he can walk on thorns etc., and can die at will.

Vyasa Bhashya (Sanskrit)

समस्तेन्द्रियवृत्तिः प्राणादिलक्षणा जीवनं, तस्य क्रिया पञ्चतयी प्राणो मुखनासिकागतिराहृदयवृत्तिः। समं नयनात्समानश्चाऽऽनाभिवृत्तिः। अपनयनादपान आपादतलवृत्तिः। उन्नयनादुदान आशिरोवृत्तिः। व्यापी व्यान इति। एषां प्रधानं प्राणः। उदानजयाज्जलपङ्ककण्टकादिष्वसङ्ग उत्क्रान्तिश्च प्रायणकाले भवति। तां वशित्वेन प्रतिपद्यते ॥ ३९ ॥

Vyasa Bhashya (English Translation)

Life is the combined functioning of all the senses characterized by Prana and the rest. Its action is fivefold: Prana is that which moves through the mouth and nose and functions down to the heart. Samana is so called because it distributes equally, and functions down to the navel. Apana is so called because it carries downward, and functions down to the soles of the feet. Udana is so called because it carries upward, and functions up to the head. Vyana is all-pervading. Among these, Prana is the chief. By mastering Udana, there is non-contact with water, mud, thorns, etc., and ascension (utkranti) at the time of death occurs. The yogi attains this through mastery. || 39 ||

Chapter link: Yoga Sutra Chapter 3