Bhagavatapurana 4.12.8

4.12.8

/0 maitreya uvāca
sa rāja-rājena varāya codito dhruvo mahā-bhāgavato mahā-matiḥ /
harau sa vavre 'calitāṃ smṛtiṃ yayā taraty ayatnena duratyayaṃ tamaḥ //

8. Maitreya said.—When thus induced by Kubera to ask for a boon, Dhruva of great wisdom, the great votary of the Lord, prayed for the uninterrupted memory of Hari, by which the jīva crosses over the darkness which is (otherwise) impassable.