A short note on slavery
1. Now a days Slavery has been abolished, at the time of Prophet peace be upon him there were many causes of slavery, such as warfare, debt (where if the debtor could not pay off his debt, he became a slave), kidnapping and raids, and poverty and need. [see Islamqa fatwa 94840]
2. Slavery was already existing (which was cultural problem for e.g Yusaf Aleh salam was bought by Aziz e Misar as a slave 1000s of years ago before Prophet Muhammad Peace be upon him) and there were two rules for prisoners of war, first is to kill them or make them slaves and do whatever you want with them, you can even hit them.
3. Islam teaches us to free the slaves [Surah al-Balad verse 12,13] Prophet peace be upon him ordered to free the slaves.[Sahih Bukhari, Eclipses, Volume 2, Book 18, Number 163][Sahih Bukhari, Food, Meals, Volume 7, Book 65, Number 286]
4. But those people who were unable to go back because of the war between the nations, Islam set the rules for them, rather then putting them into the jail. The Caliph or the leader would give them into the private custody to save them, not to make things hard for them. As it can be seen in the hadeeth
Abu Huraira reported Allah’s Messenger (may peace be upon him) as saying: “When the slave of anyone amongst you prepares food for him and he serves him after having sat close to (and undergoing the hardship of) heat and smoke, he should make him (the slave) sit along with him and make him eat (along with him), and if the food seems to run short, then he should spare some portion for him (from his own share) – (another narrator). (Translation of Sahih Muslim, The Book of Oaths (Kitab Al-Aiman), Book 015, Number 4096)”
5. Slaves can be our leaders, Abu Dharr reported: My friend (the Holy Prophet) bade me to hear and obey (the ruler) even if he is a slave having his feet and arms cut off, and observe prayer at its prescribed time. (And further said): It you find people having observed the prayer, you in fact saved your prayer, otherwise (if you join with them) that would be a Nafl prayer for you. (Muslim, Book #004, Hadith #1355)
6. Islam reduced the tendency of making slaves, It was not abolished by Islam because the concept of prisoners of wars was existing. Islam just provided the rules to free them. Islam in gradual process tried to eliminate the slavery.
7. Regarding the concubine, As it is quoted above Islam encouraged to free the slave so it is better to free her and marry as did by Prophet Peace be upon him with Saffiyah and Raihana ra and encouraged in the hadith of Sahih al-Bukhari: Narrated Abu Burda’s father: Allah’s Apostle said “Three persons will have a double reward… 3. A master of a woman-slave who teaches her good manners and educates her in the best possible way (the religion) and manumits her and then marries her.” [Volume 1, Book 3, Number 97], But even if it is not possible then after their acceptance of Islam (as mentioned by Imam Nawawi in Sharah Sahih Muslim and Imam Shafiee) do sariyyah from the word sirr, which itself means marriage, Because there was a fear of adultery, if the man or woman is not married. Islam even encouraged to abolish this rule for e.g if you break your fast then the ransom is free the slave, if you want to do righteous deed then free the slave, if you break your qasam then free the slave etc. So Islam has eliminated it by gradual process.
8. It was not permissible to have sexual intercourse with the slave women who were not from the Ahul Kitab.
Ibn Qudamah Hanbali said:
أن من حرم نكاح حرائرهم من المجوسيات ، وسائر الكوافر سوى أهل الكتاب ، لا يباح وطء الإماء منهن بملك اليمين . في قول أكثر أهل العلم ، منهم ; مرة الهمداني ، والزهري ، وسعيد بن جبير ، والأوزاعي ، والثوري ، وأبو حنيفة ، ومالك ، والشافعي . وقال ابن عبد البر : على هذا جماعة فقهاء الأمصار ، وجمهور العلماء ، وما خالفه فشذوذ لا يعد خلافا .
As for the people whose free women are impermissible for Muslims to marry of Magians and all other disbelievers apart from Christians and Jews, it is also impermissible to have sexual intercourse with the slave-women who are from among such people according to the majority of the scholars including al Hamdani, Zuhri, Saeed bin Jubayr, Awzai, Thawri, Abu Hanifa, Maalik. al Shafiee. Ibn ‘Abd Al-Barr said, “A group of renowned jurists around the (early) Islamic world (Fuqahaa’ Al-Amsaar) and the majority of scholars maintained this opinion. The opposing opinion is held only by few scholars and it is not even regarded as disagreement. [al Mughni Ibn Qudama]
What about the hadith where sahaba had sexual Intercourse with mushriqs.
Saheeh Muslim
Book 008, Number 3432:
Abu Sa’id al-Khudri (Allah her pleased with him) reported that at the Battle of Hunain Allah’s Messenger (may peace be upon him) sent an army to Autas and encountered the enemy and fought with them. Having overcome them and taken them captives, the Companions of Allah’s Messenger (may peace be upon him) seemed to refrain from having intercourse with captive women because of their husbands being polytheists. Then Allah, Most High, sent down regarding that:” And women already married, except those whom your right hands possess (iv. 24)” (i. e. they were lawful for them when their ‘Idda period came to an end).
Ibn Qudama mentioned this and said:
وقد أجبت عن حديث أبي سعيد بأجوبة ، منها أنه يحتمل أنهن أسلمن ، كذلك روي عن أحمد أنه سأله محمد بن الحكم قال : قلت لأبي عبد الله : هوازن أليس كانوا عبدة أوثان ؟ قال : لا أدري كانوا أسلموا أو لا . وقال ابن عبد البر : إباحة وطئهن منسوخة بقوله تعالى { : ولا تنكحوا المشركات حتى يؤمن } . ( 5399 )
The Hadeeth narrated by Abu Sa‘eed was met with response from the following statements: It is probable that these women had embraced Islam. It was reported about Imaam Ahmad that he was asked by Muhammad ibn Al-Hakam the following question: “From the Hawaazin tribe; were they not polytheists?” He answered that he did not know whether they had embraced Islam or not. Ibn ‘Abd Al-Barr wrote: “It should be noted that the permissibility of having intercourse with one’s polytheist captive was abrogated by the verse (that means): {And do not marry polytheistic women until they Believe.} [Quran 2:221]” [End of quote from Al-Mughni]
al Qurtubi said: Abu Umar (Ibn Abdul Barr) mentioned from al Zuhri the tabiyee that it is now allowed to have intercourse with them until they accept Islam, and he said Ibn Shihab al Zuhri knows the Maghazi and Siyar more than anyone and he also said Zuhri’s saying is refuting the one who said the sahaba had sexual intercourse with women of Autas (as mentioned in the hadith you provided) and they didn’t accept Islam. [Tafsir al Qurtubi 2:221 has a great detail in it and he includes various other evidences from the righteous predecessors, as i said it has a great detail]
Al-Qurtubi may Allaah have mercy upon him wrote: “In classical Arabic, ‘nikaah’ refers to both the marriage contract and sexual intercourse. Since Allaah, The Exalted, uses the word ‘nikaah’ in the verse (that means): {And do not make nikaah with polytheistic women until they believe}, it is deemed unlawful for a Muslim man to marry a non-Muslim woman or to have intercourse with her by virtue of ownership.” [al Qurtubi under 2:221 End of quote, Islamweb]