Bhagavatapurana 3.4.22

3.4.22

yatra nārāyaṇo devo naraś ca bhagavān ṛṣiḥ /
mṛdu tīvraṃ tapo dīrghaṃ tepāte loka-bhāvanau //

22. Badari where the glorious Lord Narayana and Nara the glorious Rishi, the two that confer blessings on the world are engaged in Tapas, which is gentle and yet hard and long (*i.e.* which will extend to the end of Kalpa).