As Muslims know, an Egyptian Ruler gave Maria the Copt and her Sister, Sirin, to Muhammad as a "Gift." Now, is it Morally Acceptable to Accept Another Human as a Gift? Would you accept another adult human as a gift?

Maria the Copt, also known as Maria al-Qibtiyya

Maria the Copt became Muhammad's sex slave. [He may have married her later, though this is highly disputed].  But let us turn our attention to her sister, Sirin.  Muhammad gave Sirin to Hassan ibn Thabit.  Debate Questions: What kind of man gives an adult woman to another man as a gift?  What did Sirin do to deserve becoming a sex slave?