Shatapatha Brahmana 14.2.1.21

14.2.1.21

svāhā sūryasya raśmaye vṛṣṭivanaya iti sūryasya ha vā eko raśmirvṛṣṭivanirnāma yenemāḥ sarvāḥ prajā bibharti tamevaitatprīṇāti tasmādāha svāhā sūryasya raśmaye vṛṣṭivanaya ityavaraṃ svāhākāraṃ karoti parāṃ devatāmasāveva bandhuḥ

'Hail to Sûrya's ray, the rain-winner!'--for one of the sun's rays is called 'rain-winner,' whereby he supports all these creatures: it is that one he thus pleases, and therefore he says, 'Hail to Sûrya's ray, the rain-winner!' The call of hail he places first, and the deity last: the significance of this is the same as before.