Friends:

What is the Third Buddhist Precept?



The 3rd Precept: One accepts the training rule of avoiding All Sexual Abuse.
One should NOT cause Pain to others or oneself in one's search for pleasure!
Avoiding sexual abuse is thus an essential core component of harmlessness!

Specifically:
One should not mate sexually with another's partner.
One should not mate sexually with minors < 16-18 years of age.
One should not have sex that bears risk of an infectious disease.
One should not mate sexually with anyone engaged, or married to another.
One should not mate sexually with those imprisoned, forced, or under the law.
One should not have sex with one's own children, or those protected by others.
One should not have sex with one's father, mother, brother, sister, uncle or aunt.
One should not have sex with those entrusted to one's parent-like responsibility.
and adoption, when working in schools, kindergartens, orphanages, churches, temples,
monasteries, youth organizations as scouts, sport-clubs, and mental institutions etc.
One should not have sex with
animals, with excrement, or with corpses.

kāmesu-micchācāra: lit. 'wrong or evil conduct with regard to sensual things';
Unlawful sexual contact refers to adultery, and to intercourse with minors
or other persons under guardianship. The abstaining from this unlawful act is
one of the 5 moral training rules (sikkhāpada) binding upon all Buddhists.
Any sexual act transgressing this rule will inevitably cause suffering later...
The monk, however, has to observe perfect chastity by living fully celibate
even without any masturbation. In many Suttas (e.g. A.X., 176) we find the
following explanation regarding correct lay Buddhist sexual discipline:
He avoids unlawful sexual intercourse, abstains from it. He has no intercourse
with girls who are still under the protection of father, or mother, brother,
sister, or relatives, nor with married women, nor female convicts, nor, lastly,
with betrothed girls. Source:  the Buddhist Dictionary:
https://What-Buddha-Said.net/library/DPPN/wtb/s_t/sikkhaa_pada.htm




"Illicit sexual behavior, when indulged in, developed, and pursued, is something
that leads to hell, leads to rebirth as a primitive animal, leads to the realm of
the hungry ghosts. The slightest of all the results coming from illicit sexual
behavior is future rivalry, and revenge, when one becomes a human being...
https://What-Buddha-Said.net/library/ati_website/html/tipitaka/an/an08/an08.040.than.html

Adultery committed repeatedly by an otherwise good person, who does not
kill, steal, lie, or intoxicate much, and who also does significantly good deeds
like giving and helping, will in this mildest case-context result in homosexual
tendency, or orientation in the next human rebirth. Pañcagatidipani.   


"Furthermore, abandoning illicit sex, the disciple of the Noble Ones abstains
from illicit sex. In doing so, he gives freedom from danger, from animosity,
freedom from oppression to limitless numbers of beings. In giving freedom
from danger, freedom from animosity, freedom from oppression to limitless
numbers of beings, he thus gains a fair share of limitless freedom from danger,
freedom from animosity, and freedom from oppression. This is the 3rd gift,
the third great benefit... and this is the sixth reward of merit...
https://What-Buddha-Said.net/library/ati_website/html/tipitaka/an/an08/an08.039.than.html



Finally: Ignoring, hiding, or not informing about own Sexually Transmitted Disease:
Knowingly engaging in a sexual contact that puts another being in danger
of getting a sexually transmitted disease, which later may make this being
suffer, and maybe even be potentially lethal (HIV/AIDS = slow-motion murder!) 
is also not only sexual abuse in the Buddhist sense, but also illegal and forbidden
by law, and thus legally punishable in most countries today...  

More on The 5 basic Precepts: The 5 Training rules (Sikkhāpada).
Best Buddhist Praxis, Buddhist Life Standards Law_3, Mighty is Morality,
The_Five_Basics, Real Buddhists takes Refuges & Precepts

What is Sexual Abuse?