Kaushitakagrihyasutra 1.12.5

1.12.5

yathā bhūmiragnigarbhā yathā dyaurindreṇa garbhiṇī vāyuryathā diśāṃ garbha evaṃ garbhe dadhāmi te 'sau iti vā \5\

Or [with]: ‘Just as the earth contains Agni in its womb, just as the sky is pregnant with Indra, just as the wind is the womb of the quarters, so do I place a child in your womb, N.N.’