CHĀNDOGYA UPANISHAD · 5.23.1

अथ याम् पञ्चमीं जुहुयात् तां जुहुयात् उदानाय स्वाहेति ।
उदानस् तृप्यति ॥

atha yām pañcamīṃ juhuyāt tāṃ juhuyāt udānāya svāheti ।
udānas tṛpyati ॥

'And he who offers the fifth oblation, should offer it to Udâna (out-breathing), saying Svâhâ. Then Udâna is satisfied,

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