Śatapatha Brāhmaṇa ("of a hundred paths") 1.7.2.11

1.7.2.11

asau vā anuvākyeyaṃ yājyā | te ubhe yoṣe tayormithunamasti vaṣaṭkāra eva tadvā eṣa eva vaṣaṭkāro ya eṣa tapati sa udyannevāmūmādhedravatyastaṃ yannimāmadhidravati tadetena vṛṣṇemām prajātim prajāyete yainayoriyam prajātiḥ

The invitatory prayer (anuvâkyâ, f.), doubtless, is yonder (sky), and the offering-prayer (yâgyâ, f.) is this (earth)--these two are females. With each of these two the vashat-call (vashatkâra, m.) makes up a pair. Now the vashat, indeed, is no other than that scorching one (the sun). When he rises he approaches yonder (sky); and when he sets he approaches this (earth): hence whatever is brought forth here by these two, that they bring forth through that male.