CHĀNDOGYA UPANISHAD · 4.8.1

मद्गुष्टे पादं वक्तेति ।
स ह श्वो भूते गा अभिप्रस्थापयां चकार ।
ता यत्राभिसायं बभूवुस् तत्राग्निम् उपसमाधाय गा उपरुध्य समिधम् आधाय पश्चाद् अग्नेः प्राङ् उपोपविवेश ॥

madguṣṭe pādaṃ vakteti ।
sa ha śvo bhūte gā abhiprasthāpayāṃ cakāra ।
tā yatrābhisāyaṃ babhūvus tatrāgnim upasamādhāya gā uparudhya samidham ādhāya paścād agneḥ prāṅ upopaviveśa ॥

'A diver-bird (Madgu, meant for Prâna) will declare to you another foot of Brahman.' (After these words of the Hamsa), Satyakâma, on the morrow, drove the cows onward. And when they came towards the evening, he lighted a fire, penned the cows, laid wood on the fire, and sat down behind the fire, looking toward the east.

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