Chandogya Upanishad 5.17

atha hovācoddālakam āruṇim gautama kaṃ tvam ātmānam upāssa iti pṛthivīm eva bhagavo rājann iti hovāca eṣa vai pratiṣṭhātmā vaiśvānaro yaṃ tvam ātmānam upāsse tasmāt tvaṃ pratiṣṭhito 'si prajayā ca paśubhiś ca

Then he said to Auddâlaka Âruni: 'O Gautama, whom do you meditate on as the Self?' He replied: 'The earth only, venerable king.' He said: 'The Self which you meditate on is the Vaisvânara Self, called Pratishthâ (firm rest). Therefore you stand firm with offspring and cattle.

atsy annaṃ paśyasi priyam atty annaṃ paśyati priyaṃ bhavaty asya brahmavarcasaṃ kule ya etam evam ātmānaṃ vaiśvānaram upāste pādau tv etāv ātmana iti hovāca pādau te vyamlāsyetāṃ yan māṃ nāgamiṣya iti

'You eat food and see your desire, and whoever thus meditates on that Vaisvânara Self, eats food and sees his desire, and has Vedic glory in his house. 'That, however, are but the feet of the Self, and your feet would have given way, if you had not come to me.'