Shatapatha Brahmana 3.5.4.16

3.5.4.16

athādhvaryuśca yajamānaśca sammṛśete | pūrvayordakṣiṇe 'dhvaryurbhavatyaparayoruttare yajamānaḥ so 'dhvaryuḥ pṛcati yajamāna kimatreti bhadramityāha tannau sahetyupāṃśvadhvaryuḥ

The Adhvaryu and Sacrificer then touch one another (with their right hands through the holes), the Adhvaryu is at the right one of those in front, and the Sacrificer at the left one of those behind. The Adhvaryu asks, 'Sacrificer, what is here?'--'Happiness!' he says.--'(Be) that ours in common!' says the Adhvaryu in a low voice.