BṚHADĀRAṆYAKA UPANISHAD · 6.4.22

हिरण्मयी अरणी याभ्यां निर्मन्थताम् अश्विनौ ।
तं ते गर्भं हवामहे दशमे मासि सूतये ।
यथाग्निगर्भा पृथिवी यथा द्यौर् ऐन्द्रेण गर्भिणी ।
वायुर् दिशां यथा गर्भ एवं गर्भं दधामि ते ऽसाव् इति ॥

hiraṇmayī araṇī yābhyāṃ nirmanthatām aśvinau ।
taṃ te garbhaṃ havāmahe daśame māsi sūtaye ।
yathāgnigarbhā pṛthivī yathā dyaur aindreṇa garbhiṇī ।
vāyur diśāṃ yathā garbha evaṃ garbhaṃ dadhāmi te ’sāv iti ॥

With twain attrition-sticks of gold The As'vin Twins twirl forth a flame; 'Tis such a germ we beg for thee, In the tenth month to be brought forth. As earth contains the germ of Fire (agni), As heaven is pregnant with the Storm (indra), As of the points the Wind (vâyu) is germ, E'en so a germ I place in thee, So-and-so!'

Robert Ernest Hume · The Thirteen Principal Upanishads (1921), Bṛhadāraṇyaka VI.4