CHĀNDOGYA UPANISHAD · 5.20.1

अथ यां द्वितीयां जुहुयात् तां जुहुयाद् व्यानाय स्वाहेति ।
व्यानस् तृप्यति ॥

atha yāṃ dvitīyāṃ juhuyāt tāṃ juhuyād vyānāya svāheti ।
vyānas tṛpyati ॥

'And he who offers the second oblation, should offer it to Vyâna (back-breathing), saying Svâhâ. Then Vyâna is satisfied,

F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)