Śatapatha Brāhmaṇa ("of a hundred paths") 1.8.3.14

1.8.3.14

so 'nakti | vyantu vayo 'ktaṃ rihāṇā iti vaya evainametadbhūtamasmānmanuṣyalokāddevalokamabhyutpātayati tannīcairiva harati dvayaṃ tadyasmānnīcairiva haredyajamāno vai prastaro 'syā evainametatpratiṣṭhāyai noddhantīho eva vṛṣṭiṃ niyacati

He anoints (each time), with the text (Vâg. S. II, 16 e), 'May (the gods) eat, licking the anointed bird!' He thereby causes it (the prastara and hence symbolically the sacrificer) to be a bird and fly up from this world of men to the world of the gods. He then draws it twice (towards the Âhavanîya) alow (near the ground). The reason why he must draw it alow (is this): the prastara is the sacrificer; and in this way he does not remove him from this firm footing of his; and he, moreover, secures rain for this locality.