तेषां ज्ञानी नित्ययुक्त एकभक्तिर्विशिष्यते ।प्रियो हि ज्ञानिनोऽत्यर्थमहं स च मम प्रियः॥
teṣāṃ jñānī nitya-yukta eka-bhaktir viśiṣyatepriyo hi jñānino ’tyartham ahaṃ sa ca mama priyaḥ
Word by word
The verse says
Of these, the one who knows stands out — always joined, devoted to one thing only. I am very dear to that person, and that person is dear to me.
In plain words
Having just levelled the four, Krishna picks one out.
The reason is not merit. It is nitya-yukta — always joined. This is the one who is not only there when something is needed.
Then the line turns both ways. Dear to me, and I to him.
Where you've felt this · in friendship
An old man runs a second-hand bookshop near where you grew up. To most people he is the man you buy books from. To one customer, over twenty years, he has become the person who puts something aside because he knows she will want it. She never asked him to do that. It grew because she kept coming back, and because he noticed her.
Going deeper
Affection running in both directions is not a small claim, and it is easy to read straight past.
Most of the book so far has described how things are — how action works, what the self is, what happens in the mind. This line describes a relationship with two sides to it. The word for dear appears twice, once in each direction. He is dear to that person; that person is dear to him.
The reason given for the preference is worth pausing on. Not that the knower is better behaved, or has earned more. Nitya-yukta — continuously joined. The others come and go with their needs, which is natural and nowhere condemned here. This one is simply always around, and a relationship with someone always around becomes a different kind of thing.
Nothing is being asked of you except regularity, which is the least glamorous and most available qualification in the book.