Maitri (Maitrāyaṇīya) Upaniṣad 6.18

6.18

tathā tatprayogakalpaḥ prāṇāyāmaḥ pratyāhāro dhyānaṃ dhāraṇā tarkaḥ samādhiḥ ṣaḍaṅgā ityucyate yogaḥ anena yadā paśyanpaśyati rukmavarṇaṃ kartāramīśaṃ puruṣaṃ brahmayonim tadā vidvānpuṇyapāpe vihāya pare'vyaye sarvamekīkaroti evaṃ hyāha
yathā parvatamādīptaṃ nāśrayanti mṛgadvijāḥ |
tadvadbrahmavido doṣā nāśrayanti kadācana ||

18. The precept for effecting this [unity] is this: restraint of the breath (prāṇāyāma), withdrawal of the senses (pratyāhāra), meditation (dhyāna), concentration (dhāraṇā), contemplation (tarka), absorption (samādhi). Such is said to be the sixfold Yoga. By this means

When a seer sees the brilliant
Maker, Lord, Person, the Brahma-source,
Then, being a knower, shaking off good and evil,
He reduces everything to unity in the supreme Imperishable.

For thus has it been said:—

As to a mountain that ’s enflamed
Deer and birds do not resort—
So, with the Brahma-knowers, faults
Do never any shelter find.