Śatapatha Brāhmaṇa ("of a hundred paths") 3.5.4.17

3.5.4.17

athāparayordakṣiṇe 'dhvaryurbhavati | pūrvayoruttare yajamānaḥ pṛcatyadhvaryo kimatreti bhadramityāha tanma iti yajamānastadyadevaṃ sammṛśete prāṇānevaitatsayujaḥ kurutastasmādime prāṇāḥ paraḥ saṃvidre 'tha yatpṛṣṭo bhadramiti pratyāha kalyāṇamevaitanmānuṣyai vāco vadati tasmātpṛṣṭo bhadramiti pratyāhātha prokṣatyeko vai prokṣaṇasya bandhurmedhyānevaitatkaroti

Thereupon the Adhvaryu is at the right one of those behind, and the Sacrificer at the left one of those in front. The Sacrificer asks, 'Adhvaryu, what is here?'--'Happiness!' he says.--'(Be) that mine!' says the Sacrificer. Now in that they thus touch one another, thereby they make the vital airs yoke-fellows: hence these vital airs meet together farther (inside). And in that, when asked, he replies, 'Happiness (bhadram),' thereby he utters the wish of 'prosperity (kalyânam)' of ordinary speech: that is why, being asked, he replies, 'Happiness.' Thereupon he sprinkles (the holes with water): one and the same forsooth is the significance of sprinkling; he thereby renders them pure.