Shatapatha Brahmana 11.1.8

Now, the gods and the Asuras, both of them sprung from Pragâpati, once strove together. Then the Asuras, even through arrogance, thinking, 'Unto whom, forsooth, should we make offering?' went on offering into their own mouths. They came to naught, even through arrogance: wherefore let no one be arrogant, for verily arrogance is the cause of ruin.

But the gods went on offering unto one another. Pragâpati gave himself up to them, and the sacrifice became theirs; for, indeed, the sacrifice is the food of the gods.

Having given himself up to the gods, he created that counterpart of himself, to wit, the sacrifice: whence people say, 'The sacrifice is Pragâpati;' for he created it as a counterpart of himself.

By this (Full and New-moon) sacrifice he redeemed himself from the gods. Now when he (the Sacrificer) enters on the fast, he thereby gives himself up to the gods, even as Pragâpati thereby gave himself up to the gods. Let him therefore endeavour to pass that night (with his mind) completely restrained, in the same way as he would proceed with (material for) an oblation, for he becomes an oblation to the gods.

And when (on the following day) he performs the sacrifice, then he redeems himself by sacrifice from the gods, even as Pragâpati thereby redeemed himself: when he takes out the material for (the chief) sacrificial dish, he redeems the sacrifice by the material for the sacrificial dish; the sacrificial dish (he redeems) by the invitatory formula, the invitatory formula by the portion cut (from the sacrificial dish), the portion by the offering-formula, the offering--formula by the Vashat-call, and the Vashat-call by the oblation. His oblation itself is still unredeemed,--

And that sacrifice of his is like a tree with its top broken off. He redeems the oblation by the Anvâhârya (mess of rice); and because he thereby supplies (anv-â-harati) what is wanting in the sacrifice, therefore it is called Anvâhârya. Thus, then, that entire sacrifice of his comes to be redeemed; and that sacrifice becomes the Sacrificer's self in yonder world. And, verily, the Sacrificer who, knowing this, performs that (offering of) redemption comes into existence in yonder world with a complete body.