Maitri (Maitrāyaṇīya) Upaniṣad 6.24

6.24

mānase ca vilīne tu yatsukhaṃ cātmasākṣikam |
tadbrahma cāmṛtaṃ śukraṃ sā gatirloka eva saḥ ||

But when the mind has been dissolved, And there is the joy whose only witness is the self— That is Brahma, the immortal, the pure! That is the way! That indeed is the world!

6.24.p1

athānyatrāpyuktam nidrevāntarhitendriyaḥ śuddhitamayā dhiyā svapna iva yaḥ paśyatīndriyabile'vivaśaḥ praṇavākhyaṃ praṇetāraṃ bhārūpaṃ vigatanidraṃ vijaraṃ vimṛtyuṃ viśokaṃ ca so'pi praṇavākhyaḥ praṇetā bhārūpaḥ vigata nidraḥ vijaraḥ vimṛtyurviśoko bhavatītyevaṃ hyāha
evaṃ prāṇamathoṅkāraṃ yasmātsarvamanekadhā |
yunakti yuñjate vāpi yasmādyoga iti smṛtaḥ ||

25. Now, it has elsewhere been said: ‘He who, with senses indrawn as in sleep, with thoughts perfectly pure as in slumber, being in the pit of senses yet not under their control, perceives Him who is called *Om*, a leader, brilliant, sleepless, ageless, deathless, sorrowless—he himself becomes called *Om*, a leader, brilliant, sleepless, ageless, deathless, sorrowless.’ For thus has it been said:—

Whereas one thus joins breath and the syllable *Om*
And all the manifold world—
Or perhaps they are joined!—
Therefore it has been declared (*smṛta*) to be Yoga (‘Joining’).