Charak Samhita
शुक्रं तस्माद्विशेषेण रक्ष्यमारोग्यमिच्छता । एवं निदानलिङ्गाभ्यामुक्तं क्लैब्यं चतुर्विधम् ॥१८७॥
which may further cause serious illness or death. Therefore shukra (semen) shall be conserved especially for those willing to conserve the health.
english translation
zukraM tasmAdvizeSeNa rakSyamArogyamicchatA । evaM nidAnaliGgAbhyAmuktaM klaibyaM caturvidham ॥187॥
hk transliteration by Sanscript