The infallible Supreme Personality of Godhead, Viṣṇu, has descended into this world by His various partial incarnations such as Lord Haṁsa [the swan], Dattātreya, the four Kumāras and our own father, the mighty Ṛṣabhadeva. By such incarnations, the Lord teaches the science of self-realization for the benefit of the whole universe. In His appearance as Hayagrīva He killed the demon Madhu and thus brought the Vedas back from the hellish planet Pātālaloka.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
हंसस्वरूप्यवददच्युत आत्मयोगं दत्तः कुमार ऋषभो भगवान् पिता नः । विष्णुः शिवाय जगतां कलयावतिर्ण- स्तेनाहृता मधुभिदा श्रुतयो हयास्ये
haṃsasvarūpyavadadacyuta ātmayogaṃ dattaḥ kumāra ṛṣabho bhagavān pitā naḥ | viṣṇuḥ śivāya jagatāṃ kalayāvatirṇa- stenāhṛtā madhubhidā śrutayo hayāsye
SB 11.4.17