Srimad-Bhagavatam: Canto 5 - Chapter 1 - Verse 27
Sanskrit:
तद्वर्षपुरुषा ऋतव्रतसत्यव्रतदानव्रतानुव्रतनामानो भगवन्तं वाय्वात्मकं प्राणायामविधूतरजस्तमस: परमसमाधिना यजन्ते ॥ २७ ॥
ITRANS:
tad-varṣa-puruṣā ṛtavrata-satyavrata-dānavratānuvrata-nāmāno bhagavantaṁ vāyv-ātmakaṁ prāṇāyāma-vidhūta-rajas-tamasaḥ parama-samādhinā yajante.
Translation:
The inhabitants of those islands are also divided into four castes — Ṛtavrata, Satyavrata, Dānavrata and Anuvrata — which exactly resemble brāhmaṇa, kṣatriya, vaiśya and śūdra. They practice prāṇāyāma and mystic yoga, and in trance they worship the Supreme Lord in the form of Vāyu.