3.11

देवान्भावयतानेन ते देवा भावयन्तु वः ।
परस्परं भावयन्तः श्रेयः परमवाप्स्यथ ॥

devān bhāvayatānena te devā bhāvayantu vaḥ
parasparaṃ bhāvayantaḥ śreyaḥ param avāpsyatha

Prajāpati (प्रजापति) is still speaking inside Kṛṣṇa's (कृष्ण) account, and the plural you is the creatures, not Arjuna (अर्जुन) alone.

The verse

By this, foster the gods, and let the gods foster you; fostering one another, you will reach the highest good.

नेपालीमा

यसद्वारा देवताहरूलाई पोस, र देवताहरूले तिमीहरूलाई पोसून्। एकअर्कालाई पोस्दै तिमीहरू परम श्रेयमा पुग्नेछौ।

Where it sits

The sacrifice is an exchange between gods and creatures, not a gift that leaves the giver poorer. 3.12 will say what the gods give back, and the name of the man who takes it without returning anything.

Split: देवान् + भावयत + अनेन + ते + देवाः + भावयन्तु + वः + परस्परम् + भावयन्तः + श्रेयः + परम् + अवाप्स्यथ

devān + bhāvayata + anena + te + devāḥ + bhāvayantu + vaḥ + parasparam + bhāvayantaḥ + śreyaḥ + param + avāpsyatha

Sanskrit, in depth

The words

देवनागरीWordGrammarSense
देवान्devānaccusative pluralthe gods.
भावयतbhāvayataimperative, 2nd plural, causative of bhū (भू)foster, make them thrive.
अनेनanenainstrumentalby this. By the sacrifice of 3.10.
तेtenominative plural of tad (तद्)those.
देवाःdevāḥnominative pluralthe gods.
भावयन्तुbhāvayantuimperative, 3rd plurallet them foster.
वःvaḥaccusative enclitic pluralyou.
परस्परम्parasparamindeclinablemutually, each the other.
भावयन्तःbhāvayantaḥpresent participle, nominative pluralfostering.
श्रेयःśreyaḥaccusative neuterthe good.
परम्paramaccusative neuterthe highest.
अवाप्स्यथavāpsyathafuture, 2nd plural of ava-āp (अव-आप्)you will obtain.

The phrases

devān bhāvayata anena (देवान् भावयत अनेन) is the command upward. Foster the gods by this. अ + अ a + a has joined bhāvayata (भावयत) and anena (अनेन).

te devā bhāvayantu vaḥ (ते देवा भावयन्तु वः) is the return. Let those gods foster you. devāḥ (देवाः) before the voiced bh (भ्) has lost its visarga: devā (देवा).

परस्परम् भावयन्तः श्रेयः परम् अवाप्स्यथ parasparaṃ bhāvayantaḥ śreyaḥ param avāpsyatha is the result of the exchange. Fostering one another, you will reach the highest good. परम् + अवाप्स्यथ param + avāpsyatha is param avāpsyatha (परमवाप्स्यथ).

Sanskrit in this line

āḥ (आः) before a voiced consonant drops the visarga and leaves ā (आ). devāḥ bhāvayantu (देवाः भावयन्तु) is recited devā bhāvayantu (देवा भावयन्तु). You met the same loss on samavetāḥ (समवेताः) in 1.1. It is the same rule, on a command.

Say it back

Two imperatives, then the future. Who fosters whom. If the line becomes "please the gods so that you may win," you have dropped parasparam (परस्परम्).