Bhagavad Gita · Chapter 2: The Path of Understanding
Bhagavad Gita 2.53
श्रुतिविप्रतिपन्ना ते यदा स्थास्यति निश्चला ।
समाधावचला बुद्धिस्तदा योगमवाप्स्यसि ॥
śrutivipratipannā te yadā sthāsyati niścalā | samādhāvacalā buddhistadā yogamavāpsyasi ||
When your understanding, now confused by all you have heard, stands unmoving and steady in concentration, then you will attain yoga.
Modern context
A mind pulled this way and that by conflicting advice has to come to rest before real practice begins. The test of yoga is steadiness: an understanding that stays put when opinions around it change.