Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.4.38

2.3.4.38

athaindrī | indro vai yajñasya devatā sendramevaitadagnyupsthānaṃ kurute kadā cana starīrasi nendra saścasi dāśuṣa iti yajamāno vai dāśvānna yajamānāya druhyasītyevaitadāhopopennu maghavanbhūya innu te dānaṃ devasya pṛcyata iti bhūyo bhūya eva na idam puṣṭaṃ kurvityevaitadāha

Then follows a verse to Indra (Vâg. S. III, 34); for Indra is the deity of the sacrifice, and with Indra therefore he now connects the fire-worship: 'At no time, O Indra, art thou barren; and never dost thou fail the worshipper--;' the worshipper, doubtless, is the sacrificer: 'never dost thou harm the sacrificer,' this is what he thereby says: '--but more and evermore is thy gift increased, O mighty god!' thereby he says, 'do thou make us ever more prosperous here!'