Śatapatha Brāhmaṇa ("of a hundred paths") 11.8.3.8

11.8.3.8

rūpameva vāyorādatta tasmādetasya lelayata ivaivopaśṛṇvanti na tvenam paśyantyāttaṃ hyasya rūpamā ha vai dviṣato bhrātṛvyasya rūpaṃ datte ya evaṃ veda

He took to himself Vâyu's form; whence people hear it (the wind), as it were, shaking, but do not see it, for its form has been taken from it; and, verily, he who knows this takes away the form of his spiteful enemy.