Bhagavad Gita 4.29 Chapter 4, Verse 29

अपाने जुह्वति प्राणं प्राणेऽपानं तथाऽपरे ।
प्राणापानगती रुद्ध्वा प्राणायामपरायणाः ॥४.२९॥

apāne juhvati prāṇaṃ prāṇe'pānaṃ tathā'pare
prāṇāpānagatī ruddhvā prāṇāyāmaparāyaṇāḥ

Meaning

Some offer the in-breath into the out-breath and the out-breath into the in-breath; devoted to breath-control, others restrain the movement of both.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 4.29 (Chapter 4, The Yoga of Knowledge and Renunciation of Action, Verse 29)