देवान्भावयतानेन ते देवा भावयन्तु वः।परस्परं भावयन्तः श्रेयः परमवाप्स्यथ॥
devān bhāvayatānena te devā bhāvayantu vaḥparasparaṃ bhāvayantaḥ śreyaḥ param avāpsyatha
Word by word
The verse says
Sustain the powers above with this, and let them sustain you. Sustaining each other, you will come to what is truly good.
In plain words
The circuit, in one line. You feed them, they feed you.
The word running through it is bhāvayantaḥ — causing to thrive, nourishing. It appears three times in three lines. Krishna is hammering it.
And the middle word is parasparam — one another, mutually. Not upward worship. An exchange that runs both ways.
Where you've felt this · in relationships
Two people keep a friendship going over years by small unequal acts. Neither is keeping score and the ledger has never balanced on any given day. Over a decade it is exactly even, and neither of them arranged that.
Going deeper
It is worth being clear-eyed about what the devas are here, because a modern reader stalls on them.
In the Vedic world they are the powers behind the working of things — fire, rain, wind, the sun. Not distant kings to be flattered but the forces the world runs on, addressed as persons.
Read that way, the verse is less exotic than it looks. It says the things that sustain you are themselves sustained by what goes back into them, and the traffic is two-way.
Parasparam is the load-bearing word. The Gita is not describing a transaction with a superior. It is describing mutual maintenance, and the next five verses extend it into a picture of the whole world as a single circulating system.
The promise attached is śreyaḥ param — the highest good. Which is the same word Arjuna asked for in verse 2. Krishna is answering the question he was actually asked, just more slowly than Arjuna wanted.