Hijab

Thank you for your question! As for the ruling of hijab on a slave woman, it is not considered obligatory on them. According to Al-Bahr az-Zakhkhaar, the awra of a slave woman is similar to that of a man outside of the prayer. This is based upon a narration in which Abu Musa mentioned this on the mimbar and was not censured by any of the other Companions, including 'Ali, upon him be peace. It is therefore taken as a proof. However, the same text also says that the awra of a slave woman is like that of the free woman in the prayer by consensus. 

And Allah knows best!

IRS  

 
Thank you for your questions!

As for the differentiation that exists, the verse in question does seemingly imply the obligation of ALL believing women to cover--irrespective of whether they are free or slaves. However, what must be understood is that a seemingly general command in the Qur'an does not always apply to slaves. For example, the obligation of zakat (Q. 2:177) requires that the believers possess wealth to distribute it, but this doesn't apply to slaves. Likewise, the obligation of kaffara for breaking an oath or unintentional manslaughter (Q. 5:89, 58:3, 4:92) requires that the believers addressed own slaves to manumit; however, this does not apply to believing slaves who are owned themselves. Similarly, the general obligation to perform the Hajj pilgrimage (Q. 3:97) does not apply to a slave due to the fact that they do not {have the means} due to their state.  

Furthermore, there is evidence in the verse you quoted (Q. 24:31) that slave women are not included in this command. If you look at all those who are exempted from her covering, the slave master is not mentioned. It is understood from other verses that the master is allowed to see the nakedness of his female slaves (Q. 23:5-6); therefore, his absence in being mentioned in this verse points to the fact that believing slave women are not addressed here. Not only that but the same verse includes male slaves {who have no desire}. Surely, this doesn't apply to a slave woman.    

This view is further supported by the narrations in which slave women are not encouraged to cover their heads. It is narrated that 'Umar commanded a group of slave women to uncover their heads and said to them: "Do not resemble free women!" (Ref. Shifaa al-Awaam, Sharh at-Tajreed). It's not that we consider 'Umar's judgement as a proof in and of itself. Rather, we consider the fact that no one objected to his actions and statements as a proof. 

As for the relationship of a slave woman and her master, a man's relationship with a non-related woman is established by marriage or ownership. Therefore, his ownership of a slave woman permits him to touch her to exclusion of others. 

And Allah knows best!

IRS