Chapter 4 · verse 29 · gita.yoga.org

Bhagavad Gita 4.29

अपाने जुह्वति प्राण प्राणेऽपानं तथाऽपरे। प्राणापानगती रुद्ध्वा प्राणायामपरायणाः

Others offer as sacrifice the outgoing breath into the incoming, and the incoming into the outgoing, restraining the flow of the outgoing and the incoming breaths, solely absorbed in the restraint of the breath.