Śāṇḍilya Upaniṣad 1.6_2

1.6_2

prāṇāpānasamāyogaḥ prāṇāyāmo bhavati | recakapūrakakumbhakabhedena sa trividhaḥ | te varṇātmakāḥ | tasmātpraṇava eva prāṇāyāmaḥ padmādyāsanasthaḥ pumānnāsāgre śaśabhṛdbimbajyotsnājālavitānitākāramūrtī raktāṅgī haṃsavāhinī daṇḍahastā bālā gāyatrī bhavati | ukāramūrtiḥ śvetāṅgī tārkṣyavāhinī yuvatī cakrahastā sāvitrī bhavati | makāramūrtiḥ kṛṣṇāṅgī vṛṣabhavāhinī vṛddhā triśūladhāriṇī sarasvatī bhavati | akārāditrayāṇāṃ sarvakāraṇamekākṣaraṃ paraṃjyotiḥ praṇavaṃ bhavatīti dhyāyet | iḍayā bāhyādvāyumāpūrya ṣoḍaśamātrābhirakāraṃ cintayanpūritaṃ vāyuṃ catuḥṣaṣṭimātrābhiḥ kumbhayitvokāraṃ dhyāyanpūritaṃ piṅgalayā dvātriṃśanmātrayā makāramūrtidhyānenaivaṃ krameṇa punaḥ punaḥ kuryāt ||

"Prāṇāyāma is said to be the union of Prāṇa and Apāna. It is of three kinds—expiration, inspiration, and cessation. They are associated with the letters of the (Samskṛṭ) alphabet (for the right performance of prāṇāyāma). Therefore Praṇava (Om) only is said to be Prāṇāyāma. Sitting in the paḍma posture, the person should meditate that there is at the tip of his nose Gāyaṭrī, a girl of red complexion surrounded by the numberless rays of the image of the moon and mounted on a hamsa (swan) and having a mace in her hand. She is the visible symbol of the letter A. The letter U has as its visible symbol Sāviṭrī, a young woman of white colour having a disk in her hand and riding on a garuda (eagle). The letter M has as its visible symbol Sarasvaṭī, an aged woman of black colour riding on a bull, having a trident in her hand. He should meditate that the single letter—the supreme light—the praṇava (Om)—is the origin or source of these three letters A, U, and M. Drawing up the air through Idā for the space of sixteen māṭrās, he should meditate on the letter A during that time; retaining the inspired air for the space of sixty-four māṭrās, he should meditate on the letter U during the time; he should then exhale the inspired air for the space of thirty-two māṭrās, meditating on the letter M during that time. He should practise this in the above order over and over again.