BṚHADĀRAṆYAKA UPANISHAD · 4.4.20

एकधैवानुद्रष्टव्यम् एतद् अप्रमयं ध्रुवम् ।
विरजः पर आकाशाद् अज आत्मा महान् ध्रुवः ॥

ekadhaivānudraṣṭavyam etad apramayaṃ dhruvam ।
virajaḥ para ākāśād aja ātmā mahān dhruvaḥ ॥

'This eternal being that can never be proved, is to be perceived in one way only; it is spotless, beyond the ether, the unborn Self, great and eternal.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)