Śatapatha Brāhmaṇa ("of a hundred paths") 3.8.2.22

3.8.2.22

athāha stokebhyo 'nubrūhīti | sa āgneyī stokebhyo 'nvāha tadyadāgneyī stokebhyo 'nvāhetaḥpradānā vai vṛṣṭirito hyagnirvṛṣṭiṃ vanute sa etai stokairetāntstokānvanute ta ete stokā varṣanti tasmādāgneyī stokebhyo 'nvāha yadā śṛtā bhavati

He then says (to the Maitrâvaruna), 'Recite to the drops!' He recites to the drops verses addressed to Agni. The reason why he recites to the drops verses addressed to Agni, is that rain originates from gifts made from this earth, for from here it is that Agni obtains the rain; by means of these drops (falling from the omentum) he obtains those (rain) drops, and those drops rain down; therefore he recites to the drops verses addressed to Agni. When it is roasted,--