Having balanced prāṇa and apāna that flow within the nose, the yogi, without laziness, should drink the air with attention at the mouth.

This verse introduces the concept of samavrtti — balanced or uniform breathing. Sama means “equal” and applies here to prāṇa and apāna, the two main currents of vital energy. Prāṇa vāyu governs inhalation and the chest region; apāna vāyu governs exhalation and the lower abdominal region.

The goal of balancing these two forces is fundamental in haṭha yoga. Normally they are in constant unequal flux. When they are balanced (samau kṛtvā), the mind automatically quiets and prāṇa can enter suṣumnā.

The phrase nāsābhyantara-cāriṇau (“that flow within the nose”) suggests that this balance is perceived in the subtle sensations of nasal breathing. A sensitive practitioner can feel the difference between prāṇic and apānic flows.

Atandritaḥ means “without laziness” or “with vigilance.” Balancing prāṇa and apāna requires continuous alert attention. Mukhāvadhānena (“with attention at the mouth”) may refer to the technique of khechari mudrā or simply to awareness of air flow.