Narasimhapurana 36.3

36.3

yathā kaurmeṇa rūpeṇa viṣṇunā mandaro dhṛtaḥ
yathā pṛthvī dhṛtā rājan vārāheṇa mahātmanā //

how Mandara was borne by Viṣṇu in the form of a tortoise; / how the earth was borne, O king, by the Great-souled One as a boar;