In general, Quranic verse claim that a free man could not be killed for killing a woman or a slave.

Quran 2:178:

يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ كُتِبَ عَلَيْكُمُ ٱلْقِصَاصُ فِى ٱلْقَتْلَى ۖ ٱلْحُرُّ بِٱلْحُرِّ وَٱلْعَبْدُ بِٱلْعَبْدِ وَٱلْأُنثَىٰ بِٱلْأُنثَىٰ ۚ

O ye who believe! Retaliation is prescribed for you in the matter of the murdered; the freeman for the freeman, and the slave for the slave, and the female for the female.

Although later coming Muslim Scholars tried to differ from it and claimed that this verse was later abrogated by verse 5:45 where Allah said "Life for a Life ٱلنَّفْسَ بِٱلنَّفْسِ", and it is a 'general order' which includes all (i.e. freeman, and slaves and females are all equal).

Ibn Kathir writes in the commentary of this verse 2:178 (link):

Allah's statement (i.e. verse 2:178): الْحُرُّ بِالْحُرِّ وَالْعَبْدُ بِالْعَبْدِ وَالأُنثَى بِالأُنثَى  (the free for the free, the slave for the slave, and the female for the female) was abrogated by the statement "Life for a Life ٱلنَّفْسَ بِٱلنَّفْسِ" (i.e. verse 5:45)

Nevertheless, the claim about abrogation from verse 5:45 is against the logic, while this verse is only speaking about the law of Jews in their book Torah, which came thousands of years before the ruling in Verse 2:178). So, how could then the ruling in verse 5:45 abrogate the ruling in verse 2:178, which came thousands of years later than the former one?

Quran 5:44-45:

إِنَّآ أَنزَلْنَا ٱلتَّوْرَىٰةَ فِيهَا هُدًى وَنُورٌ ۚ يَحْكُمُ بِهَا ٱلنَّبِيُّونَ ٱلَّذِينَ أَسْلَمُوا۟ لِلَّذِينَ هَادُوا۟ وَٱلرَّبَّٰنِيُّونَ وَٱلْأَحْبَارُ بِمَا ٱسْتُحْفِظُوا۟ مِن كِتَٰبِ ٱللَّهِ وَكَانُوا۟ عَلَيْهِ شُهَدَآءَ ۚ فَلَا تَخْشَوُا۟ ٱلنَّاسَ وَٱخْشَوْنِ وَلَا تَشْتَرُوا۟ بِـَٔايَٰتِى ثَمَنًا قَلِيلًا ۚ وَمَن لَّمْ يَحْكُم بِمَآ أَنزَلَ ٱللَّهُ فَأُو۟لَٰٓئِكَ هُمُ ٱلْكَٰفِرُونَ وَكَتَبْنَا عَلَيْهِمْ فِيهَآ أَنَّ ٱلنَّفْسَ بِٱلنَّفْسِ وَٱلْعَيْنَ بِٱلْعَيْنِ وَٱلْأَنفَ بِٱلْأَنفِ وَٱلْأُذُنَ بِٱلْأُذُنِ وَٱلسِّنَّ بِٱلسِّنِّ وَٱلْجُرُوحَ قِصَاصٌ ۚ فَمَن تَصَدَّقَ بِهِۦ فَهُوَ كَفَّارَةٌ لَّهُۥ ۚ وَمَن لَّمْ يَحْكُم بِمَآ أَنزَلَ ٱللَّهُ فَأُو۟لَٰٓئِكَ هُمُ ٱلظَّٰلِمُونَ

We sent down the Torah which contains guidance and light, ....... And there (in the Torah) We had ordained for them a life for a life, and an eye for an eye, and a nose for a nose, and an ear for an ear, and a tooth for a tooth, and for wounds retribution, though he who forgoes it out of charity, atones for his sins. And those who do not judge by God's revelations are unjust.

In simple words, the situation is like this:

  1. Muslims claim that thousands of years ago Allah made the blood of a freeman and a free woman and a slave EQUAL in Torah.
  2. But then thousands of years after that, Allah made their blood of a freeman and free woman and a slave UNEQUAL in Surah Baqara i.e. verse 2:178).
  3. But then after some time, Allah again made the blood of a freeman and a free woman and a slave EQUAL in Surah al-Maida (i.e. verse 5:45).
  4. Nevertheless, there is absolutely no hint in verse 5:45 that it is abrogating the verse 2:178, but it is simply talking about the older law of Torah. 

Therefore, it seems that ruling in verse 2:178 was absolutely not abrogated. But it was so shameful (i.e. a free man could not be killed for killing of woman or slave), that later coming Muslims tried to change it at their own in order to save the honor of their religion.

Moreover, Muslims themselves agree that verse 5:45 is not general as a free man could not be killed for killing a Kafir. It is mentioned in Sahih Bukhari, Hadith 111: وَلاَ يُقْتَلُ مُسْلِمٌ بِكَافِرٍ (A Muslim could not be killed for killing a Kafir).

Sahih Bukhari, Hadith 111:

(Ali said) ... no Muslim should be killed in Qisas (equality in punishment) for the killing of a Kafir (a disbeliever).

Therefore, here Muslims are contradicting themselves and accepting that verse 5:45 is not a general ruling, and it does not apply to the killing of Kafirs.

Similarly, Muslims also give fatwas that a free man or an owner could not be killed for killing his slave.

Imam Qurtabi gathered the fatwas of Imams in his Tafsir of Quran (link):

والجمهور من العلماء لا يقتلون الحر بالعبد ، للتنويع والتقسيم في الآية . وقال أبو ثور : لما اتفق جميعهم على أنه لا قصاص بين العبيد والأحرار فيما دون النفوس كانت النفوس أحرى بذلك …

Majority of Scholars have this opinion that none of free Muslim could be killed in Qisas (equal compensation) for killing a slave, while the verse (Quran 2:178) divided their status in this way, as Abu Thoor mentioned that majority of Ulama agree that human status of a slave is lower than that of a free person ...

And Imam Abdullah Ibn Abi Zayd writes in his book (link):

ولا يقتل حر بعبد ويقتل به العبد ولا يقتل مسلم بكافر ويقتل به الكافر ولا قصاص بين حر وعبد في جرح ولا بين مسلم وكافر ۔۔۔ ومن قتل عبدا فعليه قيمته

A free man should not be put to death for murdering a slave, although a slave should be put to death for murdering a free man. And a Muslim should not be put to death for murdering an unbeliever, although an unbeliever should be put to death for murdering a believer …

Imam Shafi’i wrote in his book al-Am (link):

وكذلك لا يقتل الرجل الحر بالعبد بحال ، ولو قتل حر ذمي عبدا مؤمنا لم يقتل به۔

A free person will not be killed for the crime of killing a slave. Even if a free Kafir Dhimmi (i.e. protected person of Kafir minority in Islamic State) kills a slave, still that Kafir Dhimmi could not be killed for this crime.

And it is written Hanbali Fiqh book “al-Insaaf” (link):

وَلَا يُقْتَلُ مُسْلِمٌ بِكَافِرٍ وَلَوْ ارْتَدَّ وَلَا حُرٌّ بِعَبْدٍ هذا الْمَذْهَبُ بِلَا رَيْبٍ وَعَلَيْهِ الْأصحاب

A Muslim could not be killed as punishment if he kills a Kafir … similarly, a free man could not be killed as punishment if he kills a slave. Indeed, this is the correct religion, upon which Sahaba (companions) acted upon.

This again proves that there is no generality in verse 5:45 .

Moreover, Muslim Scholars are unanimous that:

  • A husband could beat his wife in every matter in the name of teaching her respect. 
  • He could slap her on the face.
  • He could beat her brutally even with bruises, still he will not be punished in any way.
  • He could even break any part of her body, but still he will not be punished in any way. 
  • And a woman cannot even have a right to take divorce from such an abusive husband. 
  • If she wants her freedom from such an abusive husband, then she should offer her ransom money to him. If he accepts that money offer and divorces her, then she will become free. But if he refuses to accept the money offer, then no Islamic court or society could get her freedom from the brutal beating of the abusive husband. 

Please read the full article:The deadly COMBINATION of two Evils: Brutal BEATING of Women + Women having no right to Divorce