jñānakarmasanyāsayoga - Verse śloka 29
śloka 29
apāne juhvati prāṇaṃ prāṇe'pānaṃ tathāpare |
prāṇāpānagatī ruddhvā prāṇāyāmaparāyaṇāḥ ||4-29||
Translation
Others offer the vital breath into the apana breath, and apana into the vital breath, restraining the flow of prana and apana; they regard pranayama itself as their aim.