Of course this is not really a misunderstanding at all. Muhammad owned slaves, and the Qur’an takes the existence of slavery for granted, even as it enjoins the freeing of slaves under certain circumstances, such as the breaking of an oath: “Allah will not call you to account for what is futile in your oaths, but He will call you to account for your deliberate oaths: for expiation, feed ten indigent persons, on a scale of the average for the food of your families; or clothe them; or give a slave his freedom” (5:89).
But while the freeing of a slave or two here and there is encouraged, the institution itself is never questioned. The Qur’an even gives a man permission to have sexual relations with his slave girls as well as with his wives: “The believers must (eventually) win through, those who humble themselves in their prayers; who avoid vain talk; who are active in deeds of charity; who abstain from sex, except with those joined to them in the marriage bond, or (the captives) whom their right hands possess, for (in their case) they are free from blame…” (23:1-6). A Muslim is not to have sexual relations with a woman who is married to someone else – except a slave girl: “And all married women (are forbidden unto you) save those (captives) whom your right hands possess. It is a decree of Allah for you” (4:24).
Slavery is still practiced more or less openly today in Sudan and Mauritania, and there is evidence that slavery still continues beneath the surface in some majority-Muslim countries as well -- notably Saudi Arabia, the home of Dr. Saud Al-Fanisan, which only abolished slavery in 1962, Yemen and Oman, both of which ended legal slavery in 1970, and Niger, which didn’t abolish slavery until 2004. In Niger, the ban is widely ignored, and according to a Nigerian study, as many as one million people remain in bondage there.
"Dr. Saud Al-Fanisan, Former Dean of Islamic Law at a Saudi University: Islamic Law Permits the Possession of Slaves," from MEMRI, March 16:
Following are excerpts from a statement by Dr. Saud Al-Fanisan, former dean of Islamic law at Imam Muhammad Bin Saud Islamic University, Saudi Arabia, which aired on Al-Risala TV on March 16, 2012 :
Dr. Saud Al-Fanisan : Allah permitted the purchase and sale of slaves. Slaves are the property of their owners. This is slavery in the shari'a, yet a slave enjoys a great deal of freedom. The only thing he is deprived of is the right to own [himself]. That's it. He enjoys freedom of thought, freedom of belief, the freedom to work, the right to deny [Islam], and the right to command good and forbid evil. A slave enjoys all these liberties, so how can it be claimed that there is no freedom [in Islam]?