आहुस्त्वामृषयः सर्वे देवर्षिर्नारदस्तथा।असितो देवलो व्यासः स्वयं चैव ब्रवीषि मे॥
āhus tvām ṛṣayaḥ sarve devarṣir nāradas tathāasito devalo vyāsaḥ svayaṃ caiva bravīṣi me
Word by word
The verse says
All the sages say this of you — the divine seer Nārada, and Asita, Devala, Vyāsa. And now you are telling me so yourself.
In plain words
Arjuna lists his sources, by name.
Three sages and a divine seer, all of whom said this before. And then the last clause, which is doing something different.
He is not citing authorities to settle an argument. He is noticing that what he was told matches what he is now seeing.
Where you've felt this · in study
Everybody told you your new neighbourhood was friendly before you moved. You half believed it, in the way you half believe things people say about places. Then somebody you have never met helps you carry a wardrobe up two flights of stairs, and the thing you had been told becomes a thing you know.
Going deeper
Testimony and direct experience are being brought together here, and Arjuna is careful to keep them distinct.
He names the people who told him first. Then he says that now the person in question is saying it too, and he is present for it. The second does not make the first unnecessary — he does not drop the names — but it clearly changes their status for him.
This is how most people actually come to believe anything important. You are told it long before you are in a position to check, and what you were told shapes what you are able to notice when the moment comes.
The honest version of this is worth holding. Being told something by people you trust is not the same as knowing it, and pretending it is produces a brittle kind of certainty. But it is not nothing either. It is what gets you to the point where you could recognise the thing if you saw it.