Chandogya Upanishad 8.8.1

8.8.1

udaśarāva ātmānam avekṣya yad ātmano na vijānīthas tan me prabrūtam iti \
tau hodaśarāve avekṣāṃ cakrāte \
tau ha prajāpatir uvāca kiṃ paśyatha iti \
tau hocatuḥ sarvam evedam āvāṃ bhagava ātmānaṃ paśyāva ā lomabhyaḥ ā nakhebhyaḥ pratirūpam iti \\808.1\

'Look at yourself in a pan of water and whatever you do not understand of the Ātman, tell me that.' Then they looked in a pan of water. Prajāpati asked them, 'What do you see?' They replied, 'Revered sir, we both see the self entirely as we are, the very image even to the very hairs and nails.'