Slave

Slavery is a part of life in the Sh'areen Caliphate, especially in the household of the wealthy and the nobility. They perform a multitude of tasks but are often seen as valuable enough to not risk anything dangerous. It's easier to employ someone who will have to deal with the risk on their own. Instead, they are used for tasks that employees simply don't want to do rather than ones that would risk the slave.
Due to their expense (a slave might cost anywhere from 1,000 to 50,000 gold), they are well taken care of. While they don't have the freedom to choose their own lot in life, they are often treated better and lead easier lives than the undesired of society. No one will spit at a slave or treat them poorly, because that usually draws the ire of the owner. Instead, the slave is treated as very valuable property.
How pleasant the life of a slave depends on the kindness or their master. A kind own will make sure their slaves are reasonably happy even while performing their duties, while other owners might delight in the power over another person and treat them with cruelty or disregard for well-being as people. Most fall somewhere in-between.

Sex slaves

Since this topic comes up, yes there are plenty of slaves whose duties involve sexual services. Even amongst monogamous couples it is usually not considered cheating to be with one's slaves as long as no children come of it and the primary relationship isn't neglected. Having a sexual partner who can't say no, even to more odd requests are valued by some slave owners. That said, slaves are much too expensive to waste on something like this except for the very wealthy, or those who also have their slaves provide other tasks.
Slaves are practically never used for prostitution as it's much cheaper to find someone to do that for a salary. That said, an offer of services might be part of diplomatic or trade negotiations.