Dattatreya Yogasastra, in a dialogue form between Sankriti and Lord Dattatreya, 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 arambha, gha?a, paricaya and ni?patti avasthas. Of the Ha?hayoga practices, it elaborates mainly eight bandhas and mudras which are mahamudra, mahabandha, khecari mudra, jaladhara, uddiyana and moola bandhas, viparitakarana and vajroli.
Of yamas and niyamas the Yogasastra regards that laghvahara (eating less) and ahimsa are supreme respectively. Of all the asanas, practice of padmasana alone is highly recommended and also regarded as the destroyer of all diseases.
The Yogasastra 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.
Dattatreya Yogasastra regards praṇayama as an important practice in yoga sadhana. Padmasana is highly recommended for the practice of praṇayama. The techniques of praṇayama are fully elaborated with the inclusion of the practice of three bandhas and sahita kumbhaka (with the retention of breath) for the purification of na?is. It is further described that when the na?is 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 praṇayama 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 arambha avastha (stage). When kevala kumbhaka is perfected through further practice, he attains gha?a avastha. This is a very important stage in which prana and apana, manas and praṇa and atma and paramatma are united. It instructs further that the yogi in this stage should practice pratyahara. While practicing pratyahara, 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, ni?patti avastha 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 jivan mukta (one who is liberated while living) in this universe.
