Chāndogya Upaniṣad 2.19.2

2.19.2

sa ya evam etad yajñāyajñīyam aṅgeṣu protaṃ veda \
aṅgī bhavati \
nāṅgena vihūrchati \
sarvam āyur eti \
jyog jīvati \
mahān prajayā paśubhir bhavati \
mahān kīrtyā \
saṃvatsaraṃ majjño nāśnīyāt \
tad vratam \
majjño nāśnīyād iti vā \\219.2\

2. He who knows thus this Yajñāyajñīya Sāman as woven upon the members of the body becomes possessor of the members of his body, does not become defective in any member of the body, reaches a full length of life, lives long, becomes great in offspring and in cattle, great in fame. One should not eat of marrow for a year. That is his rule. Rather, one should not eat of marrow at all.