I have heard that the Prophet (sws) was gifted a slave girl Maria by the monarch of Egypt. If this is correct, why did not the Prophet (sws) free her and then marry her? Why did he keep her as his slave?

As has been explained several times before in this column, Islam adopted a gradual way to eradicate the evil institution of slavery, which was deeply rooted in the Arabian society. During the interim period people were allowed to keep slave women and sleep with them. This was the very reason that Maria the Coptic slave lady was not necessarily set free, since keeping slave women was totally allowed in the transitional period. Freeing her, of course, would have hurt the Egyptian king and marrying her would have increased the Prophet’s responsibilities; secondly, an example needed to be set as to how Muslims should treat their slave girls –  who in those times were treated very badly. Moreover, it is clear from the Qur’ān (33:49-52) that the Prophet (sws) could only free and marry slave girls who were made prisoners in war. He was not allowed to marry gifted slave women that had been set free.