Śatapatha Brāhmaṇa ("of a hundred paths") 1.7.3.16

1.7.3.16

tadyadete atra | yājyānuvākye avakLptatame bhavatastṛtīyasavanaṃ vai sviṣṭakṛdvaiśvadevaṃ vai tṛtīyasavanam piprīhi devāṃ uśato yaviṣṭheti tadanuvākyāyai vaiśvadevamagne yadadya viśo adhvarasya hotariti tadyājyāyai vaiśvadevaṃ tadyadete evaṃrūpe bhavatasteno ete tṛtīyasavanasya rūpaṃ tasmādvā ete atra yājyānuvākye avakLptatame bhavataḥ

The reason why on this occasion the invitatory and offering-formulas are made closely to correspond to each other (avakliptatama), is that the svishtakrit (is equivalent to) the evening libation, and the evening libation, doubtless, belongs to the Visve Devâh (the 'All-gods). 'Gladden thou the longing gods, O youngest!' this much in the invitatory formula refers to the Visve Devâh. 'O Agni, Hotri of the cult! when this day (thou comest) to the men;' this much in the offering-formula refers to the Visve Devâh. And because such is the form of these two (formulas), therefore they are of the form of the evening libation; and this is why the invitatory and offering-formulas on this occasion are made closely to correspond to each other.