Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.1.37

2.3.1.37

anenaiva juhuyāt | sajūrdevena savitreti tatsavitṛmatprasavāya sajū rātryendravatyeti tadrātryā mithunaṃ karoti sendraṃ karotīndro hi yajñasya devatā juṣāṇo agnirvetu svāheti tadagnaye pratyakṣaṃ juhoti

He may also offer (in the evening) with this text (Vâg. S. III, 10), 'Along with the divine Savitri--,' whereby it (the sacrifice) becomes possessed of Savitri for his impulsion; '--along with the Night, wedded to Indra--,' whereby he effects a union with the night, and makes it (the sacrifice) possessed of Indra, for Indra is the deity of the sacrifice; '--may Agni graciously accept! Svâhâ!' whereby he offers to Agni in a direct manner.