Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 32-33

Sanskrit:

श्रीभगवानुवाचसम आसन आसीन: समकायो यथासुखम् ।हस्तावुत्सङ्ग आधाय स्वनासाग्रकृतेक्षण: ॥ ३२ ॥प्राणस्य शोधयेन्मार्गं पूरकुम्भकरेचकै: ।विपर्ययेणापि शनैरभ्यसेन्निर्जितेन्द्रिय: ॥ ३३ ॥

ITRANS:

śrī-bhagavān uvācasama āsana āsīnaḥsama-kāyo yathā-sukhamhastāv utsaṅga ādhāyasva-nāsāgra-kṛtekṣaṇaḥ

Translation:

The Supreme Personality of Godhead said: Sitting on a level seat that is not too high or too low, keeping the body straight and erect yet comfortable, placing the two hands on one’s lap and focusing the eyes on the tip of one’s nose, one should purify the pathways of breathing by practicing the mechanical exercises of pūraka, kumbhaka and recaka, and then one should reverse the procedure (recaka, kumbhaka, pūraka). Having fully controlled the senses, one may thus practice prāṇāyāma step by step.

Purport:

According to this procedure, the hands are to be placed palms upward, one on top of the other. Thus, one may practice prāṇāyāma through mechanical breath control in order to achieve steadiness of the mind. As stated in the yoga-śāstra, antar-lakṣyo bahir-dṛṣṭiḥ sthira-cittaḥ susaṅgataḥ: “The eyes, which generally see externally, must be turned inward, and thus the mind is steadied and fully controlled.”