Devibhagavatapurana 3.13.28

3.13.28

ekasminsamaye viṣṇurvaikuṇṭhe saṃsthitaḥ purā |
sudhāsindhusthitaṃ dvīpaṃ sasmāra maṇimaṇḍitam ||

Then Bhagavân Visnu, while sitting one day in Vaikuntha, got in his mind the memory of that beautiful island, called Mani Dvîpa, adorned with precious stones, gems and jewels.