Chandogya Upanishad 7.10

āpo vāvānnād bhūyasyaḥ tasmād yadā suvṛṣṭir na bhavati vyādhīyante prāṇā annaṃ kanīyo bhaviṣyatīti atha yadā suvṛṣṭir bhavaty ānandinaḥ prāṇā bhavanty annaṃ bahu bhaviṣyatīti āpa evemā mūrtā yeyaṃ pṛthivī yad antarikṣaṃ yad dyaur yat parvatā yad devamanuṣyā yat paśavaś ca vayāṃsi ca tṛṇavanaspatayaḥ śvāpadāny ā kīṭapataṅgapipīlakam āpa evemā mūrtāḥ apa upāssveti

'Water (ap) is better than food. Therefore if there is not sufficient rain, the vital spirits fail from fear that there will be less food. But if there is sufficient rain, the vital spirits rejoice, because there will be much food. This water, on assuming different forms, becomes this earth, this sky, this heaven, the mountains, gods and men, cattle, birds, herbs and trees, all beasts down to worms, midges, and ants. Water indeed assumes all these forms. Meditate on water.

sa yo 'po brahmety upāste āpnoti sarvān kāmāṃs tṛptimān bhavati yāvad apāṃ gataṃ tatrāsya yathākāmacāro bhavati yo 'po brahmety upāste asti bhagavo 'dbhyo bhūya iti adbhyo vāva bhūyo 'stīti tan me bhagavān bravītv iti

He who meditates on water as Brahman, obtains all wishes, he becomes satisfied; he is, as it were, lord and master as far as water reaches—he who meditates on water as Brahman. 'Sir, is there something better than water?' 'Yes, there is something better than water.' 'Sir, tell it me.'