Maitri (Maitrāyaṇīya) Upaniṣad 6.36

6.36

dve vā va khalvete brahmajyotiṣo rūpake śāntamekaṃ samṛddhaṃ caikam atha yacchantaṃ tasyādhāraṃ kham atha yatsamṛddhamidaṃ tasyānnam tasmānmantrauṣadhājyāmiṣapuroḍāśasthālīpākādibhiryaṣṭavyamanta-rvedyāmāsnyavaśiṣṭairannapānaiścāsyamāhavanīyamiti matvā tejasaḥ samṛddhyai puṇyalokavijityarthāyāmṛtatvāya cātrodāharanti agnihotraṃ juhuyātsvargakāmo yamarājyamagniṣṭomenābhiyayati somarājyamukthena sūryarājyaṃ ṣoḍaśīnā svārājyamatirātreṇa prājāpatyamāsahasrasaṃvatsarāntakratuneti vartyādhārasnehayogādyathā dīpasya saṃsthitiḥ |
antaryāṇḍopayogādimau sthitāvātmaśicī tathā ||

36. Assuredly, indeed, of the light-Brahma there are these two forms: one, the Tranquil (śānta); and the other, the Abounding.

Now, of that which is the Tranquil, space (kha) is the support. And of that which is the Abounding, food here is the support.

Therefore one should offer sacrifice in the sacrificial space (vedi) with sacred verses (mantra), herbs, ghee, flesh, sacrificial cakes, boiled rice, and the like, and also—regarding the mouth as the Āhavanīya fire—with food and drink cast (avasṛṣṭa) in the mouth, for the sake of an abundance of vigor, for the winning of the holy (puṇya) world, and for immortality.

On this point they quote: ‘One who is desirous of heaven (svarga) should offer the Agnihotra sacrifice. One wins the realm of Yama with the Agniṣṭoma sacrifice, the realm of the moon (Soma) with the Uktha, the realm of the sun (sūrya) with the Shoḍaśin (the sixteen-day sacrifice), an independent realm

with the Atirātra sacrifice, that of the Lord of Creation (Prajāpati) with the sacrifice which continues to the end of a thousand years.’

As the existence of a lamp
Is because of combination of wick, support, and oil,
So these two, the self and the bright (sun),
Exist because of the combination of the Inner One and the world-egg.