Śatapatha Brāhmaṇa ("of a hundred paths") 1.7.3.13

1.7.3.13

yakṣatsvam mahimānamiti | yatra vā ado devatā āvāhayati tadapi svam mahimānamāvāhayati tadataḥ prāṅnyai kiṃ cana svāya mahimna iti kriyate tadatra tam prīṇāti tatho hāsyaiṣo 'moghāyāvāhito bhavati tasmādāha yakṣatsvam mahimānamiti

[The Hotri continues to recite]: 'May he sacrifice to his own greatness!' When, on that occasion, he asks him (Agni) to bring hither the deities, he also makes him bring hither his own greatness; but before this no worship of any kind has been offered to 'his (Agni's) own greatness:' and he therefore now gratifies him, and thus that (fire) has been established so as to prevent failure on his (the sacrificer's) part. This is the reason why he says 'may he sacrifice to his own greatness.'