Bṛhadāraṇyaka Upaniṣad ("Great Forest Teaching") 6.3.6

6.3.6

athainamācāmati tatsaviturvareṇyam | madhu vātā tāyate madhu kṣaranti sindhavaḥ | mādhvīrnaḥ santvoṣadhīḥ | bhūḥ svāhā | bhargo devasya dhīmahi | madhu naktamutoṣasomadhumatpārthivam̐ rajaḥ | madhu dyaurastu naḥ pitā | bhuvaḥ svāhā | dhiyo yo naḥpracodayāt madhumānno vanaspatirmadhumām̐3 astu sūryaḥ | mādhvīrgāvo bhavantu naḥ | svaḥ svāheti | sarvāṃ ca sāvitrīmanvāha sarvāśca madhumatīrahamevedam̐ sarvaṃ bhūyāsaṃ bhūrbhuvaḥ svaḥ svāhetyantata ācamya pāṇī prakṣālya jaghanenāgniṃ prākśirāḥsaṃviśati prātarādityamupatiṣṭhate diśāmekapuṇḍarīkamasyahaṃ manuṣyāṇāmekapuṇḍarīkaṃ bhūyāsamiti yathetametya jaghanenāgnimāsīno vam̐śaṃ japati

Then he eats it, saying: 'Tat savitur varenyam (We meditate on that adorable light)--The winds drop honey for the righteous, the rivers drop honey, may our plants be sweet as honey! Bhûh (earth) Svâhâ!
'Bhargo devasya dhîmahi (of the divine Savitri)--May the night be honey in the morning, may the air above the earth, may heaven, our father, be honey! Bhuvah (sky) Svâhâ!'
'Dhiyo yo nah prokodayât (who should rouse our thoughts)--May the tree be full of honey, may the sun be full of honey, may our cows be sweet like honey! Svah (heaven) Svâhâ!'
He repeats the whole Sâvitrî verse, and all the verses about the honey, thinking, May I be all this! Bhûr, Bhuvah, Svah, Svâhâ! Having thus swallowed all, he washes his hands, and sits down behind the altar, turning his head to the East. In the morning he worships Âditya (the sun), with the hymn, 'Thou art the best lotus of the four quarters, may I become the best lotus among men.' Then returning as he came, he sits down behind the altar and recites the genealogical list.