CHĀNDOGYA UPANISHAD · 8.6.5

अथ यत्रैतद् अस्माच् छरीराद् उत्क्रामति ।
अथैतैर् एव रश्मिभिर् ऊर्ध्वम् आक्रमते ।
स ओम् इति वा होद् वा मीयते ।
स यावत् क्षिप्येन् मनस् तावद् आदित्यं गच्छति ।
एतद् वै खलु लोकद्वारं विदुषां प्रपदनं निरोधो ऽविदुषाम् ॥

atha yatraitad asmāc charīrād utkrāmati ।
athaitair eva raśmibhir ūrdhvam ākramate ।
sa om iti vā hod vā mīyate ।
sa yāvat kṣipyen manas tāvad ādityaṃ gacchati ।
etad vai khalu lokadvāraṃ viduṣāṃ prapadanaṃ nirodho ’viduṣām ॥

But when he departs from this body, then he departs upwards by those very rays (towards the worlds which he has gained by merit, not by knowledge); or he goes out while meditating on Om (and thus securing an entrance into the Brahmaloka). And while his mind is failing, he is going to the sun. For the sun is the door of the world (of Brahman). Those who know, walk in; those who do not know, are shut out.

F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)