One verse

Bhagavad Gita 4.29

4.29

अपाने जुह्वति प्राणं प्राणेऽपानं तथापरे | प्राणापानगती रुद्ध्वा प्राणायामपरायणाः ||४-२९||

apāne juhvati prāṇaṃ prāṇe.apānaṃ tathāpare . prāṇāpānagatī ruddhvā prāṇāyāmaparāyaṇāḥ ||4-29||

apāne
in the air which acts downward
juhvati
offer
prāṇam
the air which acts outward
prāṇe
in the air going outward
apānam
the air going downward
tathā
as also
apare
others
prāṇa
of the air going outward
apāna
and the air going downward
gatī
the movement
ruddhvā
checking
prāṇa-āyāma
trance induced by stopping all breathing
parāyaṇāḥ
so inclined

Still others, who are inclined to the process of breath restraint to remain in trance, practice by offering the movement of the outgoing breath into the incoming, and the incoming breath into the outgoing, and thus at last remain in trance, stopping all breathing. Others, curtailing the eating process, offer the outgoing breath into itself as a sacrifice.