Chapter 6, Verse 18
Part of 6: Dhyān Yog — ध्यानयोगयदा विनियतं चित्तमात्मन्येवावतिष्ठते। निःस्पृहः सर्वकामेभ्यो युक्त इत्युच्यते तदा॥
yadā viniyataṁ chittam ātmanyevāvatiṣhṭhate niḥspṛihaḥ sarva-kāmebhyo yukta ityuchyate tadā
When the perfectly controlled mind rests in the Self alone, free from longing for any of the objects of desire, then it is said, 'He is united'.
Perfectly controlled mind The mind with onepointedness. When all desires for the objects of pleasure seen or unseen die, the mind becomes very peaceful and rests steadily in the Supreme Self within. As the Yogi is perfectly harmonised, as he has attained to oneness with the Self and as he has become identical with Brahman, sense phenomena and bodily affections do not disturb him. He is conscious of his immortal, imperishable and invincible nature. Yukta means united (with the Self) or harmonised or balanced. Without union with the Self neither harmony nor balance nor Samadhi is possible. (Cf. V.23VI.8)