Shatapatha Brahmana 1.1.4.19

1.1.4.19

atha śūrpamādatte | varṣavṛddhamasīti varṣavṛddhaṃ hyetadyadi naḍānāṃ yadi veṇūnāṃ yadīṣīkāṇāṃ varṣamuhyevaitā vardhayati

Thereupon he (the Adhvaryu) takes the winnowing basket, with the text (Vâg. S. I, 14 b): 'Rain-grown art thou!' For rain-grown it is indeed, whether it be made of reeds or of cane or of rushes, since it is the rain that makes these grow.