Shatapatha Brahmana 1.6.3.15

1.6.3.15

tāvenamupāvavṛtatuḥ | tāvanu sarve devāḥ preyuḥ sarvā vidyāḥ sarvaṃ yaśaḥ sarvamannādyaṃ sarvā śrīsteneṣṭvendra etadabhavadyadidamindra eṣa u paurṇamāsasya bandhuḥ sa yo haivaṃ vidvānpaurṇamāsena yajata etāṃ haiva śriyaṃ gacatyevaṃ yaśo bhavatyevamannādo bhavati

They went over to him, and after them went forth all the gods, all the sciences, all glory, all nourishment, all prosperity: thus by offering that (cake to Agni and Soma) Indra became what Indra now is. Such then is the significance of the full-moon offering; and he who, knowing this, performs the full-moon offering in this wise, attains to the same state of prosperity, becomes thus endowed with glory, becomes such a consumer of food (as Vritra).