Shatapatha Brahmana 3.8.2.21

3.8.2.21

atha sruveṇopahatyājyam | adhvaryurvapāmabhijuhotyagnirājyasya vetu svāheti tatho hāsyaite stokāḥ śṛtāḥ svāhākṛtā āhutayo bhūtvāgnim prāpnuvanti

Thereupon the Adhvaryu, having taken ghee with the dipping-spoon, pours it upon the omentum, with, 'May Agni graciously accept the ghee, Hail!' Thus those drops thereof reach the fire after becoming cooked offerings, made with Svâhâ (hail)!