Chāndogya Upaniṣad 2.13.3

2.13.3

sa ya evam etad vāmadevyaṃ mithune protaṃ veda \
mithunī bhavati \
mithunān mithunāt prajāyate \
sarvam āyur eti \
jyog jīvati \
mahān prajayā paśubhir bhavati \
mahān kīrtyā \
na kāṃcana pariharet \
tad vratam \\213.3\

2. He who knows thus this Vāmadevya Sāman as woven upon copulation comes to copulation, procreates himself from every copulation, reaches a full length of life, lives long, becomes great in offspring and in cattle, great in fame. One should never abstain from any woman. That is his rule.