Vasiṣṭha's teaching (Mahārāmāyaṇa) 6.28.40

6.28.40

tathedamalpakālasthamapi saṃlakṣyate sthiram .
vyomanyeva yathā tāpatapte saṃdṛśyate sarit .. 40

40. [Sanskrit available] The temporary world appears to be as lasting, as the river which appears in the sky under the burning sunshine. (Though in fact both of them are equally evanescent).