Khandogya-Upanishad: Second Prapathaka, Eighteenth Khanda
1. The hinkara is goats, the prastava sheep, the udgitha cows, the pratihara horses, the nidhana man. These are the Revati Samans, as interwoven in animals.
2. He who thus knows these Revatis, as interwoven in animals, becomes rich in animals, he reaches the full life, he lives long, becomes great with children and cattle, great by fame. His rule is, “Never complain of animals.”