Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.2.11

2.3.2.11

atha yatraitatpradīpto bhavati | uccairdhūmaḥ paramayā jūtyā balbalīti tarhi haiṣa bhavatīndraḥ sa yaḥ kāmayetendraiva śriyā yaśasā syāmiti tarhi ha sa juhuyātprāpnoti haivaitadannādyaṃ ya evaṃ vidvāṃstarhi juhoti

And when it is in full blaze, and the smoke whirls upwards with the utmost speed, then indeed that (fire) is Indra. And if any one wishes to be like Indra in splendour and glory, let him offer then: and, assuredly, he who, knowing this, offers then, obtains that food (object).