Shatapatha Brahmana 5.3.4.24

5.3.4.24

atha yaddhutvā-hutvā gṛhṇāti | vajro vā ājyaṃ vajreṇaivaitadājyena spṛtvā-spṛtvā svīkṛtya gṛhṇāti

And as to why he takes (water) each time after offering,--the ghee, to be sure, is a thunderbolt: having won them, one by one, by means of that thunderbolt, the ghee, and made them his own, he takes them.