Leviticus 19:20-22

And whosoever lieth carnally with a woman, that is a bondmaid, betrothed to an husband, and not at all redeemed, nor freedom given her; she shall be scourged; they shall not be put to death, because she was not free.

Whosoever lieth carnally with a ... bondmaid. Female slaves having, in a political point of view, no status, possessed no rights nor privileges. In the case supposed, no matrimonial nor pecuniary reparation was enjoined; and the only penalty for the offence was a trespass offering.