CHĀNDOGYA UPANISHAD · 2.6.2
भवन्ति हास्य पशवः पशुमान् भवति य एतद् एवं विद्वान् पशुषु पञ्चविधं सामोपास्ते ॥
bhavanti hāsya paśavaḥ paśumān bhavati ya etad evaṃ vidvān paśuṣu pañcavidhaṃ sāmopāste ॥
Animals belong to him, nay, he is rich in animals who knowing this meditates on the fivefold Sâman as animals.
F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)