Śatapatha Brāhmaṇa ("of a hundred paths") 2.6.4.8

2.6.4.8

sa yadvaiśvadevena yajate | agnireva tarhi bhavatyagnereva sāyujyaṃ salokatāṃ jayatyatha yatsākamedhairyajata indra eva tarhi bhavatīndrasyaiva sāyujyaṃ salokatāṃ jayati

And when he performs the Vaisvadeva, then he becomes Agni, and attains to union with Agni and to co-existence in his world. And when he performs the Varunapraghâsa offerings, then he becomes Varuna, and attains to union with Varuna and to co-existence in his world. And when he performs the Sâkamedha offerings, then he becomes Indra, and attains to union with Indra and to coexistence in his world.