Shatapatha Brahmana 11.1.8.4

11.1.8.4

sa etena yajñena devebhya ātmānaṃ nirakrīṇīta sa yadvratamupaiti yathaiva tatprajāpatirdevebhya ātmānam prāyacadevamevaiṣa etaddevebhya ātmānam prayacati tasmādu saṃyata evaitāṃ rātriṃ cicariṣedyathā haviṣā caredevaṃ havirhyeṣa devānām bhavati

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.