The Mukhya Upaniṣads

Maitrī · Prapāṭhaka 6 · Maitrī 6.1

Passage 18

तथा तत्प्रयोगकल्पः प्राणायामः प्रत्याहारो ध्यानं धारणा तर्कः समाधिः षडङ्गा इत्युच्यते योगः अनेन यदा पश्यन्पश्यति रुक्मवर्णं कर्तारमीशं पुरुषं ब्रह्मयोनिम् तदा विद्वान्पुण्यपापे विहाय परेऽव्यये सर्वमेकीकरोति एवं ह्याह यथा पर्वतमादीप्तं नाश्रयन्ति मृगद्विजाः ।तद्वद्ब्रह्मविदो दोषा नाश्रयन्ति कदाचन ॥ ॥६.१८ ॥

In plain words

Now the rule of its practice: restraint of breath, withdrawal of the senses, meditation, concentration, reflection and absorption — this is called the sixfold discipline. When by this a man, seeing, sees the golden-hued one, the maker, the Lord, the Person, the source of Brahman, then the knower, leaving behind good and evil, makes all one in the highest, the imperishable. So it is said: "As beasts and birds do not take shelter on a burning mountain, so faults never take shelter in a knower of Brahman."