only when four upright men bear witness that the slave actually committed adultery—explicitly describing the act of penetration—or when the slave himself confesses. In those circumstances the ḥadd is lifted from the master.
Know also that if a slave fornicates, he is liable for half the punishment prescribed for a free person, as Allah the Exalted says: “When they are married and then commit indecency—their punishment is half that of free, married women” (Q 4:25). The element of the married woman’s penalty that can be halved is the flogging; accordingly, a slave who commits adultery is to receive fifty lashes only. The scholars have added that banishment (taghrīb) is waived, because a free, unmarried fornicator is lashed one hundred times and expelled from the town for a full year, whereas banishing the slave would harm his owner and burden him with what he is not responsible for.
The master, moreover, is allowed to carry out the flogging on his own slave when the latter commits adultery, in view of the Prophet’s instruction: “When the slave-girl of any one of you fornicates, let him flog her.” Thus the master himself administers the punishment. A free person, by contrast, may be flogged only by the ruler or his deputy; even if the offender were your own son, once he has reached puberty and is of sound mind, the ḥadd may be executed only by the ruler or his delegate. The same rule applies to a brother who has come of age and is sane.
If the slave steals, however, the prescribed penalty is the amputation of the hand, and this can be performed only by the ruler or his deputy. Hence the jurists state that a master may enforce the ḥadd on his slave only when the punishment is flogging. Allah knows best.