Chandogya Upanishad 5.12

aupamanyava kaṃ tvam ātmānam upāssa iti divam eva bhagavo rājann iti hovāca eṣa vai sutejā ātmā vaiśvānaro yaṃ tvam ātmānam upāsse tasmāt tava sutaṃ prasutam āsutaṃ kule dṛśyate

'Aupamanyava, whom do you meditate on as the Self?' He replied: 'Heaven only, venerable king.' He said: 'The Self which you meditate on is the Vaisvânara Self, called Sutegas (having good light). Therefore every kind of Soma libation is seen in your house.

atsy annaṃ paśyasi priyam atty annaṃ paśyati priyam bhavaty asya brahmavarcasaṃ kule ye etam evam ātmānaṃ vaiśvānaram upāste mūdhā tv eṣa ātmana iti hovāca mūrdhā te vyapatiṣyad yan māṃ nāgamiṣya iti

'You eat food, and see your desire (a son, &c), and whoever thus meditates on that Vaisvânara Self, eats food, sees his desire, and has Vedic glory (arising from study and sacrifice) in his house. That, however, is but the head of the Self, and thus your head would have fallen (in a discussion), if you had not come to me.'