Śatapatha Brāhmaṇa ("of a hundred paths") 1.6.4.2

1.6.4.2

tamanveṣṭuṃ dadhrire | agnirdevatānāṃ hiraṇyastūpa ṛṣīṇām bṛhatī candasāṃ tamagniranuviveda tenaitāṃ rātriṃ sahājagāma sa vai devānāṃ vasurvīro hyeṣām

Agni of the deities, Hiranyastûpa of the Rishis, and the Brihatî of the metres, set about searching for him. Agni discovered him and stayed with him (as a guest) that (day and) night. He (Indra), namely, is the Vasu of the gods, for he is their hero.