Chandogya Upanishad
atha yad dvitīyam amṛtaṃ tad rudrā upajīvantīndreṇa mukhena na vai devā aśnanti na pibanti etad evāmṛtaṃ dṛṣṭvā tṛpyanti
On the second of these nectars the Rudras live, with Indra 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 white colour, and they rise from that colour.
sa ya etad evam amṛtaṃ veda rudrāṇām evaiko bhūtvendreṇaiva mukhenaitad evāmṛtaṃ dṛṣṭvā tṛpyati sa etad eva rūpam abhisaṃviśati etasmād rūpād udeti
He who thus knows this nectar, becomes one of the Rudras, with Indra at their head, he sees the nectar and rejoices. And he, having entered that colour, rises again from that colour.
sa yāvad ādityaḥ purastād udetā paścād astam etā dvis tāvad dakṣiṇata udetottarato 'stam etā rudrāṇām eva tāvad ādhipatyaṃ svārājyaṃ paryetā
So long as the sun rises in the east and sets in the west, twice as long does it rise in the south and set in the north; and so long does he follow the sovereign supremacy of the Rudras.