BṚHADĀRAṆYAKA UPANISHAD · 4.3.9

तस्य वा एतस्य पुरुषस्य द्वे एव स्थाने भवतः ।
इदं च परलोकस्थानं च ।
सन्ध्यं तृतीयं स्वप्नस्थानम् ।
तस्मिन्सन्ध्ये स्थाने तिष्ठन् उभे स्थाने पश्यतीदं च परलोकस्थानं च ।
अथ यथाक्रमो ऽयं परलोकस्थाने भवति ।
तम् आक्रमम् आक्रम्योभयान् पाप्मन आनन्दांश् च पश्यति ।
स यत्र प्रस्वपित्य् अस्य लोकस्य सर्वावतो मात्राम् अपादाय स्वयं विहत्य स्वयं निर्माय स्वेन भासा स्वेन ज्योतिषा प्रस्वपिति ।
अत्रायं पुरुषः स्वयंज्योतिर् भवति ॥

tasya vā etasya puruṣasya dve eva sthāne bhavataḥ ।
idaṃ ca paralokasthānaṃ ca ।
sandhyaṃ tṛtīyaṃ svapnasthānam ।
tasminsandhye sthāne tiṣṭhan ubhe sthāne paśyatīdaṃ ca paralokasthānaṃ ca ।
atha yathākramo ’yaṃ paralokasthāne bhavati ।
tam ākramam ākramyobhayān pāpmana ānandāṃś ca paśyati ।
sa yatra prasvapity asya lokasya sarvāvato mātrām apādāya svayaṃ vihatya svayaṃ nirmāya svena bhāsā svena jyotiṣā prasvapiti ।
atrāyaṃ puruṣaḥ svayaṃjyotir bhavati ॥

'And there are two states for that person, the one here in this world, the other in the other world, and as a third an intermediate state, the state of sleep. When in that intermediate state, he sees both those states together, the one here in this world, and the other in the other world. Now whatever his admission to the other world may be, having gained that admission, he sees both the evils and the blessings. 'And when he falls asleep, then after having taken away with him the material from the whole world, destroying and building it up again, he sleeps (dreams) by his own light. In that state the person is self-illuminated.

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