श्रुतिविप्रतिपन्ना ते यदा स्थास्यति निश्चला।समाधावचला बुद्धिस्तदा योगमवाप्स्यसि॥
śruti-vipratipannā te yadā sthāsyati niścalāsamādhāv-acalā buddhis tadā yogam avāpsyasi
Word by word
The verse says
When the scriptures have stopped pulling you about, and your mind stands still and unmoved, then you will have yoga.
In plain words
The conclusion of the argument that began at verse 39.
Two conditions. The competing voices of scripture no longer pull you around. And the mind stands still.
Then - not before - you will have yoga.
Where you've felt this · in relationships
You stop asking four different people about the same decision. Not because you finally found the right adviser. Because you can hear yourself now, and you can see that the asking was a way of not deciding.
Going deeper
Scripture is vast and it does not speak with one voice, and that creates a real problem for anyone sincerely trying to obey all of it.
Śruti-vipratipannā, the hard phrase at the centre of this verse, can mean your mind, confused by the scriptures, or your mind, no longer disturbed by their conflicting claims. Commentators divide, and the second reading fits more naturally here.
On that reading the verse names something recognisable. The ritual portions promise heaven in return for sacrifice; passages like 2.45 say go past all of that. A person trying to follow everything gets pulled several ways at once - the branching of 2.41, arriving through piety instead of through desire.
Niścalā and acalā - unmoving, unshaken - are near-synonyms set side by side for emphasis. Sanskrit doubles the word where English would reach for an adverb.
And this verse closes the section. Arjuna's reply changes the subject completely, and produces the best question in the chapter.