Here are some brief quotations from the article dealing with Sura 4, "Women", which I kindly suggest you read in full by clicking on the links below (The first link will provide a brief introduction to the whole series which the reader is asked to follow with a Qur`an of their own. Reliable translations are suggested by Mr. Spencer and can be found and read online for free).
A Worldwide Must-Read: Robert Spencer’s Blogging the Qur’an
THE WORST SURA? Robert Spencer’s Blogging the Qur’an, Sura 4: ‘Women’
The person who has two wives, but is not just between them, shall appear on the Day of Judgment in such a condition that one half of his body will be collapsing.
It is not obligatory to treat them equally, rather it is recommended. So if one does so, that is good, and if not, there is no harm on him.
One might ask why the same latitude has not been given to women as well; but the answer is simple. Notwithstanding the spiritual factor of love which influences the relations between man and woman, the determinant biological reason for the sexual urge is, in both sexes, procreation: and whereas a woman can, at one time, conceive a child from one man only and has to carry it for nine months before she can conceive another, a man can beget a child every time he cohabits with a woman. Thus, while nature would have been merely wasteful if it had produced a polygamous instinct in woman, man’s polygamous inclination is biologically justified.
During Jihad (religion war), many men and women become war captives. The Amirul Mu”minin [leader of the believers, or caliph — an office now vacant] has the choice of distributing them amongst the Mujahidin [warriors of jihad], in which event they will become the property of these Mujahidin. This enslavement is the penalty for disbelief (kufr).
None of the injunctions pertaining to slavery have been abrogated in the Shari”ah. The reason that the Muslims of today do not have slaves is because they do not engage in Jihad (religion war). Their wars are fought by the instruction of the disbelievers (kuffar) and are halted by the same felons. The Muslim [sic] have been shackled by such treaties of the disbelievers (kuffar) whereby they cannot enslave anyone in the event of a war. Muslims have been denied a great boon whereby every home could have had a slave. May Allah grant the Muslims the ability to escape the tentacles of the enemy, remain steadfast upon the Din (religion) and engage in Jihad (religion war) according to the injunctions of Shari”ah. Amen!
Following that, he lays down penalties for sexual immorality. He prescribes home imprisonment until death (unless “Allah ordain for them some (other) way”) for women found guilty of “lewdness” on the testimony of four witnesses (v. 15). According to Islamic law, these four witnesses must be male Muslims; women’s testimony is inadmissible in cases of a sexual nature, even in rape cases in which she is the victim.
Yusuf Ali: “(And last) beat them (lightly)”
Al-Hilali/Khan: “(and last) beat them (lightly, if it is useful)”
Shakir: “and beat them”
Sher Ali: “and chastise them”
Khalifa: “then you may (as a last alternative) beat them”
Arberry: “and beat them”
Rodwell: “and scourge them”
Sale: “and chastise them”
Asad: “then beat them”