Why is the punishment for adultery for slave women half that for free women?

The punishment for a fornicating slave woman is half the punishment of a free fornicating woman, as explicitly stated in the Holy Quran. This distinction in punishment between them holds profound wisdom, even if it is not immediately apparent to us. Scholars have striven to discern the facets of this wisdom. They have said that punishment is commensurate with the blessing, and the blessing of freedom is greater, thus its punishment is greater. It was also said that a free person has a greater ability to protect themselves [from sin] than a slave, and a free woman possesses modesty that deters her [from evil], unlike a slave woman. Furthermore, freedom broadens the path to what is lawful and prevents indecencies.