Dattātreya Yogaśāstra, in a dialogue form between Sānkriti and Lord Dattātreya, is a unique classical yogic text. It imparts the right concept and rational knowledge of yoga with a heavy focus on practice with great effort. It clearly outlines that everyone is entitled to yoga practice regardless of one's age, sex, faith and belief, sect and cult and tradition and religion, and robe and physical appearance.
Regarding the four stages of yoga, the text mentions ārambha, ghaṭa, paricaya and niṣpatti avasthās. Of the Haṭhayoga practices, it elaborates mainly eight bandhas and mudrās which are mahāmudra, mahābandha, khecari mudrā, jāladhara, uddiyāna and moola bandhas, viparitakarana and vajroli.
Of yamas and niyamas the Yogaśāstra regards that laghvāhāra (eating less) and ahimsā are supreme respectively. Of all the asanas, practice of padmāsana alone is highly recommended and also regarded as the destroyer of all diseases.
The Yogaśāstra emphasizes that one can not achieve success in yoga just by reading scriptures, by wearing special garbs/dresses, by repeating mantras and by worshiping Gods and deities, but by constantly practicing it without sloth.
Dattātreya Yogaśāstra regards prāṇāyāma as an important practice in yoga sādhanā. Padmāsana is highly recommended for the practice of prāṇāyāma. The techniques of prāṇāyāma are fully elaborated with the inclusion of the practice of three bandhas and sahita kumbhaka (with the retention of breath) for the purification of nāḍis. It is further described that when the nāḍis are purified, the signs of success in the body of yogi become visible. When kumbhaka practice is prolonged gradually every day, the yogi finally attains kevala kumbhaka that is the ultimate goal of prāṇāyāma practice.
The text also explains that when kevala kumbhaka is achieved, the yogi experiences several signs in his body and attains some minor siddhis. This is called the ārambha avasthā (stage). When kevala kumbhaka is perfected through further practice, he attains ghaṭa avasthā. This is a very important stage in which prāna and apāna, manas and prāṇa and ātmā and paramātmā are united. It instructs further that the yogi in this stage should practice pratyāhāra. While practicing pratyāhāra, the yogi feels unity will one and all and also he attains miraculous powers, but he is advised neither to be attached to them nor to disclose them.
The text further elaborates that when perfection is attained through practice on five elements, the yogi attains supernatural powers like anima, etc. Then the yogi should continue his practice of meditation first on saguṇa brahma and then nirguṇa brahma so he can finally attain the culmination of yoga, niṣpatti avasthā in which he realizes the union with God. After achieving his union with God, at this stage, the yogi as per his wish may leave his body or he may wander as a jīvan mukta (one who is liberated while living) in this universe.