Matsyapurana 61.39

61.39

tato 'sya varadāḥ sarve babhūvuḥ śaṃkarādayaḥ
brahmā viṣṇuśca bhagavān varadānāya jagmatuḥ
varaṃ vṛṇīṣva bhadraṃ te yadabhīṣṭaṃ ca vai mune //

When Brahmâ, Viṣṇu and Śiva went to grant him a boon and asked him to seek any boon he wished, Agastya said :—“I wish to have the privilege of moving about in the Vimânas on the Dakṣiṇâchala mount, till a thousand Brahmâs come and go in turn for 25 crores of times; and those who worship me at the time of the appearance of my Vimâna, should be the monarchs of all the seven realms, till the time of the re-establishment of fresh sovereignty in the seven climes.”—39-41.