Khandogya-Upanishad: Second Prapathaka, Nineteenth Khanda
1. The hinkara is hair, the prastiva skin, the udgitha flesh, the pratihara bone, the nidhana marrow. That is the Yagnayagniya Saman, as interwoven in the members of the body.
2. He who thus knows the Yagnayagniya, as interwoven in the members of the body, becomes possessed of strong limbs, he is not crippled in any limb, he reaches the full life, he lives long, becomes great with children and cattle, great by fame. His rule is, “Do not eat marrow for a year,” or “Do not eat marrow at all.”