Chandogya Upanishad 3.8

atha yat tṛtīyam amṛtaṃ tad ādityā upajīvanti varuṇena mukhena na vai devā aśnanti na pibanti etad evāmṛtaṃ dṛṣṭvā tṛpyanti

On the third of these nectars the Âdityas live, with Varuna at their head. True, the Devas do not eat or drink, but they enjoy by seeing the nectar.

ta etad eva rūpam abhisaṃviśanti etasmād rūpād udyanti

They enter into that (dark) colour, and they rise from that colour.

sa ya etad evam amṛtaṃ vedādityānām evaiko bhūtvā varuṇenaiva mukhenaitad evāmṛtaṃ dṛṣṭvā tṛpyati sa etad eva rūpam abhisaṃviśati etasmād rūpād udeti

He who thus knows this nectar, becomes one of the Âdityas, with Varuna at their head, he sees the nectar and rejoices. And he, having entered that colour, rises again from that colour.

sa yāvad ādityo dakṣiṇata udetottarato 'stam etā dvis tāvat paścād udetā purastād astam etādityānām eva tāvad ādhipatyaṃ svārājyaṃ paryetā

So long as the sun rises in the south and sets in the north, twice as long does it rise in the west and set in the east; and so long does he follow the sovereign supremacy of the Âdityas.