Chāndogya Upaniṣad 3.8.3

3.8.3

sa ya etad evam amṛtaṃ vedādityānām evaiko bhūtvā varuṇenaiva mukhenaitad evāmṛtaṃ dṛṣṭvā tṛpyati \
sa etad eva rūpam abhisaṃviśati \
etasmād rūpād udeti \\308.3\

3. He who knows thus that nectar becomes one of the Ādityas themselves and through Varuṇa as his mouth is satisfied merely with seeing that nectar. He enters that very form and comes forth from that form.